Anti-IL-22RA antibodies and binding partners and methods of using in inflammation

ABSTRACT

The present invention relates to blocking, inhibiting, reducing, antagonizing or neutralizing the activity of IL-22, IL-20, or both IL-20 and IL-22 polypeptide molecules. IL-20 and IL-22 are cytokines that are involved in inflammatory processes and human disease. IL-22RA (zcytor11) is a common receptor for IL-20 and IL-22. The present invention includes anti-IL-22RA antibodies and binding partners, as well as methods for antagonizing IL-22 or both IL-20 and IL-22 using such antibodies and binding partners.

REFERENCE TO RELATED APPLICATIONS

This patent application is a divisional of U.S. patent application Ser.No. 12/423,699, filed Apr. 14, 2009, which is a divisional of U.S.patent application Ser. No. 11/256,499, filed Oct. 21, 2005, now U.S.Pat. No. 7,537,761, which claims the benefit of U.S. ProvisionalApplication Ser. No. 60/621,553, filed Oct. 22, 2004, all of which areherein incorporated by reference.

BACKGROUND OF THE INVENTION

Cytokines are soluble, small proteins that mediate a variety ofbiological effects, including the regulation of the growth anddifferentiation of many cell types (see, for example, Arai et al., Annu.Rev. Biochem. 59:783 (1990); Mosmann, Curr. Opin. Immunol. 3:311 (1991);Paul and Seder, Cell 76:241 (1994)). Proteins that constitute thecytokine group include interleukins, interferons, colony stimulatingfactors, tumor necrosis factors, and other regulatory molecules. Forexample, human interleukin-17 is a cytokine which stimulates theexpression of interleukin-6, intracellular adhesion molecule 1,interleukin-8, granulocyte macrophage colony-stimulating factor, andprostaglandin E2 expression, and plays a role in the preferentialmaturation of CD34+ hematopoietic precursors into neutrophils (Yao etal., J. Immunol. 155:5483 (1995); Fossiez et al., J. Exp. Med. 183:2593(1996)).

Receptors that bind cytokines are typically composed of one or moreintegral membrane proteins that bind the cytokine with high affinity andtransduce this binding event to the cell through the cytoplasmicportions of the certain receptor subunits. Cytokine receptors have beengrouped into several classes on the basis of similarities in theirextracellular ligand binding domains. For example, the receptor chainsresponsible for binding and/or transducing the effect of interferons aremembers of the class II cytokine receptor family, based upon acharacteristic 200 residue extracellular domain.

The demonstrated in vivo activities of cytokines and their receptorsillustrate the clinical potential of, and need for, other cytokines,cytokine receptors, cytokine agonists, and cytokine antagonists. Forexample, demonstrated in vivo activities of the pro-inflammatorycytokine family illustrates the enormous clinical potential of, and needfor antagonists of pro-inflammatory molecules. The present inventionaddresses these needs by providing antagonists to pro-inflammatorycytokines IL-20 and IL-22. Such antagonists of the present invention,which may block, inhibit, reduce, antagonize or neutralize the activityof IL-22, IL-20, or both IL-20 and IL-22, include soluble IL-22RAreceptors and neutralizing anti-IL-22RA antibodies. The inventionfurther provides uses therefor in inflammatory disease, as well asrelated compositions and methods.

DETAILED DESCRIPTION OF THE INVENTION

1. Overview

Amongst other inventions, the present invention provides novel uses fora soluble receptor, designated “Zcytor11” or “IL-22RA” and neutralizingantibodies to IL-22RA cytokine receptors. The present invention alsoprovides soluble IL-22RA polypeptide fragments and fusion proteins, foruse in human inflammatory and autoimmune diseases. The anti-IL-22RAantibodies, and soluble IL-22RA receptors of the present invention,including the neutralizing anti-IL-22RA antibodies of the presentinvention, can be used to block, inhibit, reduce, antagonize orneutralize the activity of either IL-22 or IL-20, or both IL-20 andIL-22 in the treatment of specific human diseases such as psoriasis,psoriatic arthritis, arthritis, endotoxemia, inflammatory bowel disease(IBD), colitis, and other inflammatory conditions disclosed herein.

An illustrative nucleotide sequence that encodes human Zcytor11(IL-22RA) is provided by SEQ ID NO:1; the encoded polypeptide is shownin SEQ ID NO:2. IL-22RA is a receptor subunit for both IL-20 and IL-22.Zcytor11 (IL-22RA) is disclosed in commonly owned U.S. Pat. No.5,965,704, commonly owned WIPO publication WO 02/12345, and commonlyowned WIPO publication WO 02/072607. Analysis of a human cDNA cloneencoding IL-22RA (SEQ ID NO:1) revealed an open reading frame encoding574 amino acids (SEQ ID NO:2) comprising an extracellular ligand-bindingdomain of approximately 211 amino acid residues (residues 18-228 of SEQID NO:2; SEQ ID NO:3), a transmembrane domain of approximately 23 aminoacid residues (residues 229-251 of SEQ ID NO:2), and an intracellulardomain of approximately 313 amino acid residues (residues 252 to 574 ofSEQ ID NO:2). Thus molecules of the present invention includepolypepetides that include a cytokine binding domain comprising aminoacids residues 18-228 of SEQ ID NO:2; SEQ ID NO:3. In one embodiment ofthe soluble receptor of the present invention, the soluble IL-22R isfused to the constant region of the heavy chain (representative shown inSEQ ID NO:4). Those skilled in the art will recognize that these domainboundaries are approximate. Deletion of residues from the ends of thedomains is possible.

As described below, the present invention provides isolated polypeptidescomprising an amino acid sequence that is at least 70%, at least 80%, orat least 90%, or greater than 95%, such as 96%, 97%, 98%, or greaterthan 99% or more identical to a reference amino acid sequence of 18-228of SEQ ID NO:2, which is also shown as SEQ ID NO:3, wherein the isolatedpolypeptide specifically binds with an antibody that specifically bindswith a polypeptide comprising the amino acid sequence of SEQ ID NO:3.Illustrative polypeptides include polypeptides comprising either aminoacid residues SEQ ID NO:3 or amino acid residues SEQ ID NO:3. Moreover,the present invention also provides isolated polypeptides as disclosedabove that bind IL-22 (e.g., human IL-22 polypeptide sequence as shownin SEQ ID NO:6). The human IL-22 polynucleotide sequence is shown in SEQID NO:5. The mouse IL-22 polynucleotide sequence is shown in SEQ IDNO:10, and corresponding polypeptide is shown in SEQ ID NO:11. Thepresent invention also provides isolated polypeptides as disclosed abovethat bind IL-20 (e.g., human IL-20 polypeptide sequence as shown in SEQID NO:8; WIPO Publication No. WO 99/27103). The human IL-20polynucleotide sequence is shown in SEQ ID NO:7.

The present invention also provides isolated polypeptides and epitopescomprising at least 15 contiguous amino acid residues of an amino acidsequence of SEQ ID NO:3. Illustrative polypeptides include polypeptidesthat either comprise, or consist of SEQ ID NO:3, an antigenic epitopethereof, or a functional IL-20 or IL-22 binding fragment thereof.Moreover, the present invention also provides isolated polypeptides asdisclosed above that bind to, block, inhibit, reduce, antagonize orneutralize the activity of IL-22 or IL-20.

The present invention also includes variant IL-22RA polypeptides,wherein the amino acid sequence of the variant polypeptide shares anidentity with the amino acid residues of SEQ ID NO:3 selected from thegroup consisting of at least 70% identity, at least 80% identity, atleast 90% identity, at least 95% identity, or greater than 95% identity,such as 96%, 97%, 98%, or greater than 99% or more identity, and whereinany difference between the amino acid sequence of the variantpolypeptide and the corresponding amino acid sequence of SEQ ID NO:3 isdue to one or more conservative amino acid substitutions. Suchconservative amino acid substitutions are described herein. Moreover,the present invention also provides isolated polypeptides as disclosedabove that bind to, block, inhibit, reduce, antagonize or neutralize theactivity of IL-22 or IL-20.

The present invention further provides antibodies and antibody fragmentsthat specifically bind with such polypeptides. Exemplary antibodiesinclude neutralizing antibodies, polyclonal antibodies, murinemonoclonal antibodies, humanized antibodies derived from murinemonoclonal antibodies, and human monoclonal antibodies. Illustrativeantibody fragments include F(ab′)₂, F(ab)₂, Fab′, Fab, Fv, scFv, andminimal recognition units. Neutralizing antibodies preferably bindIL-22RA such that the interaction of IL-20 and IL-22 with IL-22RA isblocked, inhibited, reduced, antagonized or neutralized; anti-IL-22RAneutralizing antibodies such that the binding of either IL-20 or IL-22to IL-22RA is blocked, inhibited, reduced, antagonized or neutralizedare also encompassed by the present invention. That is, the neutralizinganti-IL-22RA antibodies of the present invention can either either bind,block, inhibit, reduce, antagonize or neutralize each of IL-20 or IL-22singly, or bind, block, inhibit, reduce, antagonize or neutralize IL-20and IL-22 together. The present invention further includes compositionscomprising a carrier and a peptide, polypeptide, or antibody describedherein.

In addition, the present invention provides pharmaceutical compositionscomprising a pharmaceutically acceptable carrier and at least one ofsuch an expression vector or recombinant virus comprising suchexpression vectors. The present invention further includespharmaceutical compositions, comprising a pharmaceutically acceptablecarrier and a polypeptide or antibody described herein.

The present invention also contemplates anti-idiotype antibodies, oranti-idiotype antibody fragments, that specifically bind an antibody orantibody fragment that specifically binds a polypeptide comprising theamino acid sequence of SEQ ID NO:3 or a fragment thereof. An exemplaryanti-idiotype antibody binds with an antibody that specifically binds apolypeptide consisting of SEQ ID NO:3.

The present invention also provides fusion proteins, comprising aIL-22RA polypeptide and an immunoglobulin moiety. In such fusionproteins, the immunoglobulin moiety may be an immunoglobulin heavy chainconstant region, such as a human F_(c) fragment. The present inventionfurther includes isolated nucleic acid molecules that encode such fusionproteins.

The present invention also provides polyclonal and monoclonal antibodiesthat bind to polypeptides comprising an IL-22RA extracellular domainsuch as monomeric, homodimeric, heterodimeric and multimeric receptors,including soluble receptors. Moreover, such antibodies can be usedantagonize the binding of IL-22RA ligands, IL-22 (SEQ ID NO:6), andIL-20 (SEQ ID NO:8), individually or together to the IL-22RA receptor.

Moreover, over expression or upregulation of IL-22 and IL-20 was shownin human psoriatic lesions and human atopic dermatitis skin samples,suggesting that IL-22, like IL-20 is also involved in human psoriasis,atopic dermatitis or other inflammatory diseases of the skin andepithelial tissues. Moreover, as described herein, over expression ofIL-20 or IL-22 in transgenic mice showed epidermal thickening and immunecell involvement indicative of a psoriatic phenotype; and in additioninjection of IL-22 into normal mice showed epidermal thickening andimmune cell involvement indicative of a psoriatic phenotype which wasablated by the soluble receptor antagonist IL-22RA2 (zcytor16; WIPOPublication No. WO 01/40467). Such in vivo data further suggests thatthe pro-inflammatory IL-22 is involved in psoriasis, atopic dermatitisor other inflammatory diseases of the skin and epithelial tissues. Assuch, antagonists to IL-22 and IL-20 activity, such as IL-22RA solublereceptors and antibodies thereto including the anti-human-IL-22RAmonoclonal and neutralizing antibodies of the present invention, areuseful in therapeutic treatment of inflammatory diseases, particularlyas antagonists to both IL-22 and IL-20 singly or together in thetreatment of psoriasis. Moreover, antagonists to IL-22 activity, such asIL-22RA soluble receptors and antibodies thereto including theanti-human-IL-22RA monoclonal and neutralizing antibodies of the presentinvention, are useful in therapeutic treatment of other inflammatorydiseases for example as bind, block, inhibit, reduce, antagonize orneutralize IL-22 and IL-20 (either individually or together) in thetreatment of atopic dermatitis, IBD, colitis, Endotoxemia, arthritis,rheumatoid arthritis, and psoriatic arthritis adult respiratory disease(ARD), septic shock, multiple organ failure, inflammatory lung injurysuch as asthma or bronchitis, bacterial pneumonia, psoriasis, eczema,atopic and contact dermatitis, and inflammatory bowel disease such asulcerative colitis and Crohn's disease.

These and other aspects of the invention will become evident uponreference to the following detailed description. In addition, variousreferences are identified below and are incorporated by reference intheir entirety.

2. Definitions

In the description that follows, a number of terms are used extensively.The following definitions are provided to facilitate understanding ofthe invention.

As used herein, “nucleic acid” or “nucleic acid molecule” refers topolynucleotides, such as deoxyribonucleic acid (DNA) or ribonucleic acid(RNA), oligonucleotides, fragments generated by the polymerase chainreaction (PCR), and fragments generated by any of ligation, scission,endonuclease action, and exonuclease action. Nucleic acid molecules canbe composed of monomers that are naturally-occurring nucleotides (suchas DNA and RNA), or analogs of naturally-occurring nucleotides (e.g.,α-enantiomeric forms of naturally-occurring nucleotides), or acombination of both. Modified nucleotides can have alterations in sugarmoieties and/or in pyrimidine or purine base moieties. Sugarmodifications include, for example, replacement of one or more hydroxylgroups with halogens, alkyl groups, amines, and azido groups, or sugarscan be functionalized as ethers or esters. Moreover, the entire sugarmoiety can be replaced with sterically and electronically similarstructures, such as aza-sugars and carbocyclic sugar analogs. Examplesof modifications in a base moiety include alkylated purines andpyrimidines, acylated purines or pyrimidines, or other well-knownheterocyclic substitutes. Nucleic acid monomers can be linked byphosphodiester bonds or analogs of such linkages. Analogs ofphosphodiester linkages include phosphorothioate, phosphorodithioate,phosphoroselenoate, phosphorodiselenoate, phosphoroanilothioate,phosphoranilidate, phosphoramidate, and the like. The term “nucleic acidmolecule” also includes so-called “peptide nucleic acids,” whichcomprise naturally-occurring or modified nucleic acid bases attached toa polyamide backbone. Nucleic acids can be either single stranded ordouble stranded.

The term “complement of a nucleic acid molecule” refers to a nucleicacid molecule having a complementary nucleotide sequence and reverseorientation as compared to a reference nucleotide sequence. For example,the sequence 5′ ATGCACGGG 3′ is complementary to 5′ CCCGTGCAT 3′.

The term “degenerate nucleotide sequence” denotes a sequence ofnucleotides that includes one or more degenerate codons as compared to areference nucleic acid molecule that encodes a polypeptide. Degeneratecodons contain different triplets of nucleotides, but encode the sameamino acid residue (i.e., GAU and GAC triplets each encode Asp).

The term “structural gene” refers to a nucleic acid molecule that istranscribed into messenger RNA (mRNA), which is then translated into asequence of amino acids characteristic of a specific polypeptide.

An “isolated nucleic acid molecule” is a nucleic acid molecule that isnot integrated in the genomic DNA of an organism. For example, a DNAmolecule that encodes a growth factor that has been separated from thegenomic DNA of a cell is an isolated DNA molecule. Another example of anisolated nucleic acid molecule is a chemically-synthesized nucleic acidmolecule that is not integrated in the genome of an organism. A nucleicacid molecule that has been isolated from a particular species issmaller than the complete DNA molecule of a chromosome from thatspecies.

A “nucleic acid molecule construct” is a nucleic acid molecule, eithersingle- or double-stranded, that has been modified through humanintervention to contain segments of nucleic acid combined and juxtaposedin an arrangement not existing in nature.

“Linear DNA” denotes non-circular DNA molecules having free 5′ and 3′ends. Linear DNA can be prepared from closed circular DNA molecules,such as plasmids, by enzymatic digestion or physical disruption.

“Complementary DNA (cDNA)” is a single-stranded DNA molecule that isformed from an mRNA template by the enzyme reverse transcriptase.Typically, a primer complementary to portions of mRNA is employed forthe initiation of reverse transcription. Those skilled in the art alsouse the term “cDNA” to refer to a double-stranded DNA moleculeconsisting of such a single-stranded DNA molecule and its complementaryDNA strand. The term “cDNA” also refers to a clone of a cDNA moleculesynthesized from an RNA template.

A “promoter” is a nucleotide sequence that directs the transcription ofa structural gene. Typically, a promoter is located in the 5′ non-codingregion of a gene, proximal to the transcriptional start site of astructural gene. Sequence elements within promoters that function in theinitiation of transcription are often characterized by consensusnucleotide sequences. These promoter elements include RNA polymerasebinding sites, TATA sequences, CAAT sequences, differentiation-specificelements (DSEs; McGehee et al., Mol. Endocrinol. 7:551 (1993)), cyclicAMP response elements (CREs), serum response elements (SREs; Treisman,Seminars in Cancer Biol. 1:47 (1990)), glucocorticoid response elements(GREs), and binding sites for other transcription factors, such asCRE/ATF (O'Reilly et al., J. Biol. Chem. 267:19938 (1992)), AP2 (Ye etal., J. Biol. Chem. 269:25728 (1994)), SP1, cAMP response elementbinding protein (CREB; Loeken, Gene Expr. 3:253 (1993)) and octamerfactors (see, in general, Watson et al., eds., Molecular Biology of theGene, 4th ed. (The Benjamin/Cummings Publishing Company, Inc. 1987), andLemaigre and Rousseau, Biochem. J. 303:1 (1994)). If a promoter is aninducible promoter, then the rate of transcription increases in responseto an inducing agent. In contrast, the rate of transcription is notregulated by an inducing agent if the promoter is a constitutivepromoter. Repressible promoters are also known.

A “core promoter” contains essential nucleotide sequences for promoterfunction, including the TATA box and start of transcription. By thisdefinition, a core promoter may or may not have detectable activity inthe absence of specific sequences that may enhance the activity orconfer tissue specific activity.

A “regulatory element” is a nucleotide sequence that modulates theactivity of a core promoter. For example, a regulatory element maycontain a nucleotide sequence that binds with cellular factors enablingtranscription exclusively or preferentially in particular cells,tissues, or organelles. These types of regulatory elements are normallyassociated with genes that are expressed in a “cell-specific,”“tissue-specific,” or “organelle-specific” manner.

An “enhancer” is a type of regulatory element that can increase theefficiency of transcription, regardless of the distance or orientationof the enhancer relative to the start site of transcription.

“Heterologous DNA” refers to a DNA molecule, or a population of DNAmolecules, that does not exist naturally within a given host cell. DNAmolecules heterologous to a particular host cell may contain DNA derivedfrom the host cell species (i.e., endogenous DNA) so long as that hostDNA is combined with non-host DNA (i.e., exogenous DNA). For example, aDNA molecule containing a non-host DNA segment encoding a polypeptideoperably linked to a host DNA segment comprising a transcriptionpromoter is considered to be a heterologous DNA molecule. Conversely, aheterologous DNA molecule can comprise an endogenous gene operablylinked with an exogenous promoter. As another illustration, a DNAmolecule comprising a gene derived from a wild-type cell is consideredto be heterologous DNA if that DNA molecule is introduced into a mutantcell that lacks the wild-type gene.

A “polypeptide” is a polymer of amino acid residues joined by peptidebonds, whether produced naturally or synthetically. Polypeptides of lessthan about 10 amino acid residues are commonly referred to as“peptides.”

A “protein” is a macromolecule comprising one or more polypeptidechains. A protein may also comprise non-peptidic components, such ascarbohydrate groups. Carbohydrates and other non-peptidic substituentsmay be added to a protein by the cell in which the protein is produced,and will vary with the type of cell. Proteins are defined herein interms of their amino acid backbone structures; substituents such ascarbohydrate groups are generally not specified, but may be presentnonetheless.

A peptide or polypeptide encoded by a non-host DNA molecule is a“heterologous” peptide or polypeptide.

A “cloning vector” is a nucleic acid molecule, such as a plasmid,cosmid, or bacteriophage, that has the capability of replicatingautonomously in a host cell. Cloning vectors typically contain one or asmall number of restriction endonuclease recognition sites that allowinsertion of a nucleic acid molecule in a determinable fashion withoutloss of an essential biological function of the vector, as well asnucleotide sequences encoding a marker gene that is suitable for use inthe identification and selection of cells transformed with the cloningvector. Marker genes typically include genes that provide tetracyclineresistance or ampicillin resistance.

An “expression vector” is a nucleic acid molecule encoding a gene thatis expressed in a host cell. Typically, an expression vector comprises atranscription promoter, a gene, and a transcription terminator. Geneexpression is usually placed under the control of a promoter, and such agene is said to be “operably linked to” the promoter. Similarly, aregulatory element and a core promoter are operably linked if theregulatory element modulates the activity of the core promoter.

A “recombinant host” is a cell that contains a heterologous nucleic acidmolecule, such as a cloning vector or expression vector. In the presentcontext, an example of a recombinant host is a cell that producesIL-22RA from an expression vector. In contrast, IL-22RA can be producedby a cell that is a “natural source” of IL-22RA, and that lacks anexpression vector.

“Integrative transformants” are recombinant host cells, in whichheterologous DNA has become integrated into the genomic DNA of thecells.

A “fusion protein” is a hybrid protein expressed by a nucleic acidmolecule comprising nucleotide sequences of at least two genes. Forexample, a fusion protein can comprise at least part of a IL-22RApolypeptide fused with a polypeptide that binds an affinity matrix. Sucha fusion protein provides a means to isolate large quantities of IL-22RAusing affinity chromatography.

The term “receptor” denotes a cell-associated protein that binds to abioactive molecule termed a “ligand.” This interaction mediates theeffect of the ligand on the cell. Receptors can be membrane bound,cytosolic or nuclear; monomeric (e.g., thyroid stimulating hormonereceptor, beta-adrenergic receptor) or multimeric (e.g., PDGF receptor,growth hormone receptor, IL-3 receptor, GM-CSF receptor, G-CSF receptor,erythropoietin receptor and IL-6 receptor). Membrane-bound receptors arecharacterized by a multi-domain structure comprising an extracellularligand-binding domain and an intracellular effector domain that istypically involved in signal transduction. In certain membrane-boundreceptors, the extracellular ligand-binding domain and the intracellulareffector domain are located in separate polypeptides that comprise thecomplete functional receptor.

In general, the binding of ligand to receptor results in aconformational change in the receptor that causes an interaction betweenthe effector domain and other molecule(s) in the cell, which in turnleads to an alteration in the metabolism of the cell. Metabolic eventsthat are often linked to receptor-ligand interactions include genetranscription, phosphorylation, dephosphorylation, increases in cyclicAMP production, mobilization of cellular calcium, mobilization ofmembrane lipids, cell adhesion, hydrolysis of inositol lipids andhydrolysis of phospholipids.

A “soluble receptor” is a receptor polypeptide that is not bound to acell membrane. Soluble receptors are most commonly ligand-bindingreceptor polypeptides that lack transmembrane and cytoplasmic domains,and other linkage to the cell membrane such as via glycophosphoinositol(gpi). Soluble receptors can comprise additional amino acid residues,such as affinity tags that provide for purification of the polypeptideor provide sites for attachment of the polypeptide to a substrate, orimmunoglobulin constant region sequences. Many cell-surface receptorshave naturally occurring, soluble counterparts that are produced byproteolysis or translated from alternatively spliced mRNAs. Solublereceptors can be monomeric, homodimeric, heterodimeric, or multimeric,with multimeric receptors generally not comprising more than 9 subunits,preferably not comprising more than 6 subunits, and most preferably notcomprising more than 3 subunits. Receptor polypeptides are said to besubstantially free of transmembrane and intracellular polypeptidesegments when they lack sufficient portions of these segments to providemembrane anchoring or signal transduction, respectively. Solublereceptors of class I and class II cytokine receptors generally comprisethe extracellular cytokine binding domain free of a transmembrane domainand intracellular domain. For example, representative soluble receptorsinclude soluble receptors for CRF2-4 (a.k.a., IL-10RB) (GenbankAccession No. Z17227) as shown in SEQ ID NO:44 and SEQ ID NO:45; asoluble receptor for IL-10RA (Genbank Accession Nos. U00672 andNM_(—)001558) as shown in SEQ ID NO:46; a soluble receptor for pDIRS1(a.k.a., IL-20RB) (Genbank Accession No. AY358305) as shown in SEQ IDNO:47; and a soluble receptor for IL-22RA (U.S. Pat. No. 5,965,704) asshown in SEQ ID NO:3. It is well within the level of one of skill in theart to delineate what sequences of a known class I or class II cytokinesequence comprise the extracellular cytokine binding domain free of atransmembrane domain and intracellular domain. Moreover, one of skill inthe art using the genetic code can readily determine polynucleotidesthat encode such soluble receptor polypeptides.

The term “secretory signal sequence” denotes a DNA sequence that encodesa peptide (a “secretory peptide”) that, as a component of a largerpolypeptide, directs the larger polypeptide through a secretory pathwayof a cell in which it is synthesized. The larger polypeptide is commonlycleaved to remove the secretory peptide during transit through thesecretory pathway.

An “isolated polypeptide” is a polypeptide that is essentially free fromcontaminating cellular components, such as carbohydrate, lipid, or otherproteinaceous impurities associated with the polypeptide in nature.Typically, a preparation of isolated polypeptide contains thepolypeptide in a highly purified form, i.e., at least about 80% pure, atleast about 90% pure, at least about 95% pure, greater than 95% pure,such as 96%, 97%, or 98% or more pure, or greater than 99% pure. One wayto show that a particular protein preparation contains an isolatedpolypeptide is by the appearance of a single band following sodiumdodecyl sulfate (SDS)-polyacrylamide gel electrophoresis of the proteinpreparation and Coomassie Brilliant Blue staining of the gel. However,the term “isolated” does not exclude the presence of the samepolypeptide in alternative physical forms, such as dimers oralternatively glycosylated or derivatized forms.

The terms “amino-terminal” and “carboxyl-terminal” are used herein todenote positions within polypeptides. Where the context allows, theseterms are used with reference to a particular sequence or portion of apolypeptide to denote proximity or relative position. For example, acertain sequence positioned carboxyl-terminal to a reference sequencewithin a polypeptide is located proximal to the carboxyl terminus of thereference sequence, but is not necessarily at the carboxyl terminus ofthe complete polypeptide.

The term “expression” refers to the biosynthesis of a gene product. Forexample, in the case of a structural gene, expression involvestranscription of the structural gene into mRNA and the translation ofmRNA into one or more polypeptides.

The term “splice variant” is used herein to denote alternative forms ofRNA transcribed from a gene. Splice variation arises naturally throughuse of alternative splicing sites within a transcribed RNA molecule, orless commonly between separately transcribed RNA molecules, and mayresult in several mRNAs transcribed from the same gene. Splice variantsmay encode polypeptides having altered amino acid sequence. The termsplice variant is also used herein to denote a polypeptide encoded by asplice variant of an mRNA transcribed from a gene.

As used herein, the term “immunomodulator” includes cytokines, stem cellgrowth factors, lymphotoxins, co-stimulatory molecules, hematopoieticfactors, and the like, and synthetic analogs of these molecules.

The term “complement/anti-complement pair” denotes non-identicalmoieties that form a non-covalently associated, stable pair underappropriate conditions. For instance, biotin and avidin (orstreptavidin) are prototypical members of a complement/anti-complementpair. Other exemplary complement/anti-complement pairs includereceptor/ligand pairs, antibody/antigen (or hapten or epitope) pairs,sense/antisense polynucleotide pairs, and the like. Where subsequentdissociation of the complement/anti-complement pair is desirable, thecomplement/anti-complement pair preferably has a binding affinity ofless than 10⁹ M⁻¹.

An “anti-idiotype antibody” is an antibody that binds with the variableregion domain of an immunoglobulin. In the present context, ananti-idiotype antibody binds with the variable region of an anti-IL-22RAantibody, and thus, an anti-idiotype antibody mimics an epitope ofIL-22RA.

An “antibody fragment” is a portion of an antibody such as F(ab′)₂,F(ab)₂, Fab′, Fab, and the like. Regardless of structure, an antibodyfragment binds with the same antigen that is recognized by the intactantibody. For example, an anti-IL-22RA monoclonal antibody fragmentbinds with an epitope of IL-22RA.

The term “antibody fragment” also includes a synthetic or a geneticallyengineered polypeptide that binds to a specific antigen, such aspolypeptides consisting of the light chain variable region, “Fv”fragments consisting of the variable regions of the heavy and lightchains, recombinant single chain polypeptide molecules in which lightand heavy variable regions are connected by a peptide linker (“scFvproteins”), and minimal recognition units consisting of the amino acidresidues that mimic the hypervariable region.

A “chimeric antibody” is a recombinant protein that contains thevariable domains and complementary determining regions derived from arodent antibody, while the remainder of the antibody molecule is derivedfrom a human antibody.

“Humanized antibodies” are recombinant proteins in which murinecomplementarity determining regions of a monoclonal antibody have beentransferred from heavy and light variable chains of the murineimmunoglobulin into a human variable domain. Construction of humanizedantibodies for therapeutic use in humans that are derived from murineantibodies, such as those that bind to or neutralize a human protein, iswithin the skill of one in the art.

As used herein, a “therapeutic agent” is a molecule or atom which isconjugated to an antibody moiety to produce a conjugate which is usefulfor therapy. Examples of therapeutic agents include drugs, toxins,immunomodulators, chelators, boron compounds, photoactive agents ordyes, and radioisotopes.

A “detectable label” is a molecule or atom which can be conjugated to anantibody moiety to produce a molecule useful for diagnosis. Examples ofdetectable labels include chelators, photoactive agents, radioisotopes,fluorescent agents, paramagnetic ions, or other marker moieties.

The term “affinity tag” is used herein to denote a polypeptide segmentthat can be attached to a second polypeptide to provide for purificationor detection of the second polypeptide or provide sites for attachmentof the second polypeptide to a substrate. In principal, any peptide orprotein for which an antibody or other specific binding agent isavailable can be used as an affinity tag. Affinity tags include apoly-histidine tract, protein A (Nilsson et al., EMBO J. 4:1075 (1985);Nilsson et al., Methods Enzymol. 198:3 (1991)), glutathione Stransferase (Smith and Johnson, Gene 67:31 (1988)), Glu-Glu affinity tag(Grussenmeyer et al., Proc. Natl. Acad. Sci. USA 82:7952 (1985)),substance P, FLAG peptide (Hopp et al., Biotechnology 6:1204 (1988)),streptavidin binding peptide, or other antigenic epitope or bindingdomain. See, in general, Ford et al., Protein Expression andPurification 2:95 (1991). DNA molecules encoding affinity tags areavailable from commercial suppliers (e.g., Pharmacia Biotech,Piscataway, N.J.).

A “naked antibody” is an entire antibody, as opposed to an antibodyfragment, which is not conjugated with a therapeutic agent. Nakedantibodies include both polyclonal and monoclonal antibodies, as well ascertain recombinant antibodies, such as chimeric and humanizedantibodies.

As used herein, the term “antibody component” includes both an entireantibody and an antibody fragment.

An “immunoconjugate” is a conjugate of an antibody component with atherapeutic agent or a detectable label.

As used herein, the term “antibody fusion protein” refers to arecombinant molecule that comprises an antibody component and a IL-22RApolypeptide component. Examples of an antibody fusion protein include aprotein that comprises a IL-22RA extracellular domain, and either an Fcdomain or an antigen-binding region.

A “target polypeptide” or a “target peptide” is an amino acid sequencethat comprises at least one epitope, and that is expressed on a targetcell, such as a tumor cell, or a cell that carries an infectious agentantigen. T cells recognize peptide epitopes presented by a majorhistocompatibility complex molecule to a target polypeptide or targetpeptide and typically lyse the target cell or recruit other immune cellsto the site of the target cell, thereby killing the target cell.

An “antigenic peptide” is a peptide which will bind a majorhistocompatibility complex molecule to form an MHC-peptide complex whichis recognized by a T cell, thereby inducing a cytotoxic lymphocyteresponse upon presentation to the T cell. Thus, antigenic peptides arecapable of binding to an appropriate major histocompatibility complexmolecule and inducing a cytotoxic T cells response, such as cell lysisor specific cytokine release against the target cell which binds orexpresses the antigen. The antigenic peptide can be bound in the contextof a class I or class II major histocompatibility complex molecule, onan antigen presenting cell or on a target cell.

In eukaryotes, RNA polymerase II catalyzes the transcription of astructural gene to produce mRNA. A nucleic acid molecule can be designedto contain an RNA polymerase II template in which the RNA transcript hasa sequence that is complementary to that of a specific mRNA. The RNAtranscript is termed an “anti-sense RNA” and a nucleic acid moleculethat encodes the anti-sense RNA is termed an “anti-sense gene.”Anti-sense RNA molecules are capable of binding to mRNA molecules,resulting in an inhibition of mRNA translation.

An “anti-sense oligonucleotide specific for IL-22RA” or a “IL-22RAanti-sense oligonucleotide” is an oligonucleotide having a sequence (a)capable of forming a stable triplex with a portion of the IL-22RA gene,or (b) capable of forming a stable duplex with a portion of an mRNAtranscript of the IL-22RA gene.

A “ribozyme” is a nucleic acid molecule that contains a catalyticcenter. The term includes RNA enzymes, self-splicing RNAs, self-cleavingRNAs, and nucleic acid molecules that perform these catalytic functions.A nucleic acid molecule that encodes a ribozyme is termed a “ribozymegene.”

An “external guide sequence” is a nucleic acid molecule that directs theendogenous ribozyme, RNase P, to a particular species of intracellularmRNA, resulting in the cleavage of the mRNA by RNase P. A nucleic acidmolecule that encodes an external guide sequence is termed an “externalguide sequence gene.”

The term “variant IL-22RA gene” refers to nucleic acid molecules thatencode a polypeptide having an amino acid sequence that is amodification of SEQ ID NO:3. Such variants include naturally-occurringpolymorphisms of IL-22RA genes, as well as synthetic genes that containconservative amino acid substitutions of the amino acid sequence of SEQID NO:3. Additional variant forms of IL-22RA genes are nucleic acidmolecules that contain insertions or deletions of the nucleotidesequences described herein. A variant IL-22RA gene can be identified,for example, by determining whether the gene hybridizes with a nucleicacid molecule having the nucleotide sequence of SEQ ID NO:1, or itscomplement, under stringent conditions.

Alternatively, variant IL-22RA genes can be identified by sequencecomparison. Two amino acid sequences have “100% amino acid sequenceidentity” if the amino acid residues of the two amino acid sequences arethe same when aligned for maximal correspondence. Similarly, twonucleotide sequences have “100% nucleotide sequence identity” if thenucleotide residues of the two nucleotide sequences are the same whenaligned for maximal correspondence. Sequence comparisons can beperformed using standard software programs such as those included in theLASERGENE bioinformatics computing suite, which is produced by DNASTAR(Madison, Wis.). Other methods for comparing two nucleotide or aminoacid sequences by determining optimal alignment are well-known to thoseof skill in the art (see, for example, Peruski and Peruski, The Internetand the New Biology: Tools for Genomic and Molecular Research (ASMPress, Inc. 1997), Wu et al. (eds.), “Information Superhighway andComputer Databases of Nucleic Acids and Proteins,” in Methods in GeneBiotechnology, pages 123-151 (CRC Press, Inc. 1997), and Bishop (ed.),Guide to Human Genome Computing, 2nd Edition (Academic Press, Inc.1998)). Particular methods for determining sequence identity aredescribed below.

Regardless of the particular method used to identify a variant IL-22RAgene or variant IL-22RA polypeptide, a variant gene or polypeptideencoded by a variant gene may be functionally characterized the abilityto bind specifically to an anti-IL-22RA antibody. A variant IL-22RA geneor variant IL-22RA polypeptide may also be functionally characterizedthe ability to bind to its ligand, IL-22, using a biological orbiochemical assay described herein.

The term “allelic variant” is used herein to denote any of two or morealternative forms of a gene occupying the same chromosomal locus.Allelic variation arises naturally through mutation, and may result inphenotypic polymorphism within populations. Gene mutations can be silent(no change in the encoded polypeptide) or may encode polypeptides havingaltered amino acid sequence. The term allelic variant is also usedherein to denote a protein encoded by an allelic variant of a gene.

The term “ortholog” denotes a polypeptide or protein obtained from onespecies that is the functional counterpart of a polypeptide or proteinfrom a different species. Sequence differences among orthologs are theresult of speciation.

“Paralogs” are distinct but structurally related proteins made by anorganism. Paralogs are believed to arise through gene duplication. Forexample, α-globin, β-globin, and myoglobin are paralogs of each other.

The present invention includes functional fragments of IL-22RA genes.Within the context of this invention, a “functional fragment” of aIL-22RA gene refers to a nucleic acid molecule that encodes a portion ofa IL-22RA polypeptide which is a domain described herein or at leastspecifically binds with an anti-IL-22RA antibody.

Due to the imprecision of standard analytical methods, molecular weightsand lengths of polymers are understood to be approximate values. Whensuch a value is expressed as “about” X or “approximately” X, the statedvalue of X will be understood to be accurate to ±10%.

3. Production of IL-22RA Polynucleotides or Genes

Nucleic acid molecules encoding a human IL-22RA gene can be obtained byscreening a human cDNA or genomic library using polynucleotide probesbased upon SEQ ID NO:1. These techniques are standard andwell-established, and may be accomplished using cloning kits availableby commercial suppliers. See, for example, Ausubel et al. (eds.), ShortProtocols in Molecular Biology, 3^(rd) Edition, John Wiley & Sons 1995;Wu et al., Methods in Gene Biotechnology, CRC Press, Inc. 1997; Aviv andLeder, Proc. Nat'l Acad. Sci. USA 69:1408 (1972); Huynh et al.,“Constructing and Screening cDNA Libraries in λgt10 and λgt11,” in DNACloning: A Practical Approach Vol. I, Glover (ed.), page 49 (IRL Press,1985); Wu (1997) at pages 47-52.

Nucleic acid molecules that encode a human IL-22RA gene can also beobtained using the polymerase chain reaction (PCR) with oligonucleotideprimers having nucleotide sequences that are based upon the nucleotidesequences of the IL-22RA gene or cDNA. General methods for screeninglibraries with PCR are provided by, for example, Yu et al., “Use of thePolymerase Chain Reaction to Screen Phage Libraries,” in Methods inMolecular Biology, Vol. 15: PCR Protocols: Current Methods andApplications, White (ed.), Humana Press, Inc., 1993. Moreover,techniques for using PCR to isolate related genes are described by, forexample, Preston, “Use of Degenerate Oligonucleotide Primers and thePolymerase Chain Reaction to Clone Gene Family Members,” in Methods inMolecular Biology, Vol 15: PCR Protocols: Current Methods andApplications, White (ed.), Humana Press, Inc. 1993. As an alternative, aIL-22RA gene can be obtained by synthesizing nucleic acid moleculesusing mutually priming long oligonucleotides and the nucleotidesequences described herein (see, for example, Ausubel (1995)).Established techniques using the polymerase chain reaction provide theability to synthesize DNA molecules at least two kilobases in length(Adang et al., Plant Molec. Biol. 21:1131 (1993), Bambot et al., PCRMethods and Applications 2:266 (1993), Dillon et al., “Use of thePolymerase Chain Reaction for the Rapid Construction of SyntheticGenes,” in Methods in Molecular Biology, Vol 15: PCR Protocols: CurrentMethods and Applications, White (ed.), pages 263-268, (Humana Press,Inc. 1993), and Holowachuk et al., PCR Methods Appl. 4:299 (1995)). Forreviews on polynucleotide synthesis, see, for example, Glick andPasternak, Molecular Biotechnology, Principles and Applications ofRecombinant DNA (ASM Press 1994), Itakura et al., Annu. Rev. Biochem.53:323 (1984), and Climie et al., Proc. Nat'l Acad. Sci. USA 87:633(1990).

4. Production of IL-22RA Gene Variants

The present invention provides a variety of nucleic acid molecules,including DNA and RNA molecules, that encode the IL-22RA polypeptidesdisclosed herein. Those skilled in the art will readily recognize that,in view of the degeneracy of the genetic code, considerable sequencevariation is possible among these polynucleotide molecules. Moreover,the present invention also provides isolated soluble monomeric,homodimeric, heterodimeric and multimeric receptor polypeptides thatcomprise at least one IL-22RA receptor subunit that is substantiallyhomologous to the receptor polypeptide of SEQ ID NO:3. Thus, the presentinvention contemplates IL-22RA polypeptide-encoding nucleic acidmolecules comprising degenerate nucleotides of SEQ ID NO:1, and theirRNA equivalents.

Table 1 sets forth the one-letter codes to denote degenerate nucleotidepositions. “Resolutions” are the nucleotides denoted by a code letter.“Complement” indicates the code for the complementary nucleotide(s). Forexample, the code Y denotes either C or T, and its complement R denotesA or G, A being complementary to T, and G being complementary to C.

TABLE 1 Nucleotide Resolution Complement Resolution A A T T C C G G G GC C T T A A R A|G Y C|T Y C|T R A|G M A|C K G|T K G|T M A|C S C|G S C|GW A|T W A|T H A|C|T D A|G|T B C|G|T V A|C|G V A|C|G B C|G|T D A|G|T HA|C|T N A|C|G|T N A|C|G|T

The degenerate codons, encompassing all possible codons for a givenamino acid, are set forth in Table 2.

TABLE 2 One Amino Letter Degenerate Acid Code Codons Codon Cys C TGC TGTTGY Ser S AGC AGT TCA TCC TCG TCT WSN Thr T ACA ACC ACG ACT ACN Pro PCCA CCC CCG CCT CCN Ala A GCA GCC GCG GCT GCN Gly G GGA GGC GGG GGT GGNAsn N AAC AAT AAY Asp D GAC GAT GAY Glu E GAA GAG GAR Gln Q CAA CAG CARHis H CAC CAT CAY Arg R AGA AGG CGA CGC CGG CGT MGN Lys K AAA AAG AARMet M ATG ATG Ile I ATA ATC ATT ATH Leu L CTA CTC CTG CTT TTA TTG YTNVal V GTA GTC GTG GTT GTN Phe F TTC TTT TTY Tyr Y TAC TAT TAY Trp W TGGTGG Ter • TAA TAG TGA TRR Asn|Asp B RAY Glu|Gln Z SAR Any X NNN

One of ordinary skill in the art will appreciate that some ambiguity isintroduced in determining a degenerate codon, representative of allpossible codons encoding an amino acid. For example, the degeneratecodon for serine (WSN) can, in some circumstances, encode arginine(AGR), and the degenerate codon for arginine (MGN) can, in somecircumstances, encode serine (AGY). A similar relationship existsbetween codons encoding phenylalanine and leucine. Thus, somepolynucleotides encompassed by the degenerate sequence may encodevariant amino acid sequences, but one of ordinary skill in the art caneasily identify such variant sequences by reference to the amino acidsequences of SEQ ID NO:3. Variant sequences can be readily tested forfunctionality as described herein.

Different species can exhibit “preferential codon usage.” In general,see, Grantham et al., Nucl. Acids Res. 8:1893 (1980), Haas et al. Curr.Biol. 6:315 (1996), Wain-Hobson et al., Gene 13:355 (1981), Grosjean andFiers, Gene 18:199 (1982), Holm, Nuc. Acids Res. 14:3075 (1986),Ikemura, J. Mol. Biol. 158:573 (1982), Sharp and Matassi, Curr. Opin.Genet. Dev. 4:851 (1994), Kane, Curr. Opin. Biotechnol. 6:494 (1995),and Makrides, Microbiol. Rev. 60:512 (1996). As used herein, the term“preferential codon usage” or “preferential codons” is a term of artreferring to protein translation codons that are most frequently used incells of a certain species, thus favoring one or a few representativesof the possible codons encoding each amino acid (See Table 2). Forexample, the amino acid threonine (Thr) may be encoded by ACA, ACC, ACG,or ACT, but in mammalian cells ACC is the most commonly used codon; inother species, for example, insect cells, yeast, viruses or bacteria,different Thr codons may be preferential. Preferential codons for aparticular species can be introduced into the polynucleotides of thepresent invention by a variety of methods known in the art. Introductionof preferential codon sequences into recombinant DNA can, for example,enhance production of the protein by making protein translation moreefficient within a particular cell type or species. Therefore, thedegenerate codon sequences disclosed herein serve as a template foroptimizing expression of polynucleotides in various cell types andspecies commonly used in the art and disclosed herein. Sequencescontaining preferential codons can be tested and optimized forexpression in various species, and tested for functionality as disclosedherein.

A IL-22RA-encoding cDNA can be isolated by a variety of methods, such asby probing with a complete or partial human cDNA or with one or moresets of degenerate probes based on the disclosed sequences. A cDNA canalso be cloned using the polymerase chain reaction with primers designedfrom the representative human IL-22RA sequences disclosed herein. Inaddition, a cDNA library can be used to transform or transfect hostcells, and expression of the cDNA of interest can be detected with anantibody to IL-22RA polypeptide.

Those skilled in the art will recognize that the sequence disclosed inSEQ ID NO:1 represents a single allele of human IL-22RA, and thatallelic variation and alternative splicing are expected to occur.Allelic variants of this sequence can be cloned by probing cDNA orgenomic libraries from different individuals according to standardprocedures. Allelic variants of the nucleotide sequences disclosedherein, including those containing silent mutations and those in whichmutations result in amino acid sequence changes, are within the scope ofthe present invention, as are proteins which are allelic variants of theamino acid sequences disclosed herein. cDNA molecules generated fromalternatively spliced mRNAs, which retain the properties of the IL-22RApolypeptide are included within the scope of the present invention, asare polypeptides encoded by such cDNAs and mRNAs. Allelic variants andsplice variants of these sequences can be cloned by probing cDNA orgenomic libraries from different individuals or tissues according tostandard procedures known in the art.

Using the methods discussed above, one of ordinary skill in the art canprepare a variety of polypeptides that comprise a soluble IL-22RAreceptor subunit that is substantially homologous to SEQ ID NO:1, orthat encodes amino acids of SEQ ID NO:3, or allelic variants thereof andretain the ligand-binding properties of the wild-type IL-22RA receptor.Such polypeptides may also include additional polypeptide segments asgenerally disclosed herein.

Within certain embodiments of the invention, the isolated nucleic acidmolecules can hybridize under stringent conditions to nucleic acidmolecules comprising nucleotide sequences disclosed herein. For example,such nucleic acid molecules can hybridize under stringent conditions tonucleic acid molecules comprising the nucleotide sequence of SEQ IDNO:1, or to nucleic acid molecules comprising a nucleotide sequencecomplementary to SEQ ID NO:1, or fragments thereof.

In general, stringent conditions are selected to be about 5° C. lowerthan the thermal melting point (T_(m)) for the specific sequence at adefined ionic strength and pH. The T_(m) is the temperature (underdefined ionic strength and pH) at which 50% of the target sequencehybridizes to a perfectly matched probe. Following hybridization, thenucleic acid molecules can be washed to remove non-hybridized nucleicacid molecules under stringent conditions, or under highly stringentconditions. See, for example, Sambrook et al., Molecular Cloning: ALaboratory Manual, Second Edition (Cold Spring Harbor Press 1989);Ausubel et al., (eds.), Current Protocols in Molecular Biology (JohnWiley and Sons, Inc. 1987); Berger and Kimmel (eds.), Guide to MolecularCloning Techniques, (Academic Press, Inc. 1987); and Wetmur, Crit. Rev.Biochem. Mol. Biol. 26:227 (1990)). Sequence analysis software such asOLIGO 6.0 (LSR; Long Lake, Minn.) and Primer Premier 4.0 (PremierBiosoft International; Palo Alto, Calif.), as well as sites on theInternet, are available tools for analyzing a given sequence andcalculating T_(m) based on user-defined criteria. It is well within theabilities of one skilled in the art to adapt hybridization and washconditions for use with a particular polynucleotide hybrid.

The present invention also provides isolated IL-22RA polypeptides thathave a substantially similar sequence identity to the polypeptides ofSEQ ID NO:3, or their orthologs. The term “substantially similarsequence identity” is used herein to denote polypeptides having at least70%, at least 80%, at least 90%, at least 95%, such as 96%, 97%, 98%, orgreater than 95% sequence identity to the sequences shown in SEQ IDNO:3, or their orthologs. For example, variant and orthologous IL-22RAreceptors can be used to generate an immune response and raisecross-reactive antibodies to human IL-22RA. Such antibodies can behumanized, and modified as described herein, and used therapeutically totreat psoriasis, psoriatic arthritis, IBD, colitis, endotoxemia as wellas in other therapeutic applications described herein.

The present invention also contemplates IL-22RA variant nucleic acidmolecules that can be identified using two criteria: a determination ofthe similarity between the encoded polypeptide with the amino acidsequence of SEQ ID NO:3, and a hybridization assay. Such IL-22RAvariants include nucleic acid molecules (1) that remain hybridized witha nucleic acid molecule having the nucleotide sequence of SEQ ID NO:1(or its complement) under stringent washing conditions, in which thewash stringency is equivalent to 0.5x-2x SSC with 0.1% SDS at 55-65° C.,and (2) that encode a polypeptide having at least 70%, at least 80%, atleast 90%, at least 95%, or greater than 95% such as 96%, 97%, 98%, or99%, sequence identity to the amino acid sequence of SEQ ID NO:3.Alternatively, IL-22RA variants can be characterized as nucleic acidmolecules (1) that remain hybridized with a nucleic acid molecule havingthe nucleotide sequence of SEQ ID NO:1 (or its complement) under highlystringent washing conditions, in which the wash stringency is equivalentto 0.1x-0.2x SSC with 0.1% SDS at 50-65° C., and (2) that encode apolypeptide having at least 70%, at least 80%, at least 90%, at least95% or greater than 95%, such as 96%, 97%, 98%, or 99% or greater,sequence identity to the amino acid sequence of SEQ ID NO:3.

Percent sequence identity is determined by conventional methods. See,for example, Altschul et al., Bull. Math. Bio. 48:603 (1986), andHenikoff and Henikoff, Proc. Natl. Acad. Sci. USA 89:10915 (1992).Briefly, two amino acid sequences are aligned to optimize the alignmentscores using a gap opening penalty of 10, a gap extension penalty of 1,and the “BLOSUM62” scoring matrix of Henikoff and Henikoff (ibid.) asshown in Table 3 (amino acids are indicated by the standard one-lettercodes). The percent identity is then calculated as: ([Total number ofidentical matches]/[length of the longer sequence plus the number ofgaps introduced into the longer sequence in order to align the twosequences])(100).

TABLE 3 A R N D C Q E G H I L K M F P S T W Y V A 4 R −1 5 N −2 0 6 D −2−2 1 6 C 0 −3 −3 −3 9 Q −1 1 0 0 −3 5 E −1 0 0 2 −4 2 5 G 0 −2 0 −1 −3−2 −2 6 H −2 0 1 −1 −3 0 0 −2 8 I −1 −3 −3 −3 −1 −3 −3 −4 −3 4 L −1 −2−3 −4 −1 −2 −3 −4 −3 2 4 K −1 2 0 −1 −3 1 1 −2 −1 −3 −2 5 M −1 −1 −2 −3−1 0 −2 −3 −2 1 2 −1 5 F −2 −3 −3 −3 −2 −3 −3 −3 −1 0 0 −3 0 6 P −1 −2−2 −1 −3 −1 −1 −2 −2 −3 −3 −1 −2 −4 7 S 1 −1 1 0 −1 0 0 0 −1 −2 −2 0 −1−2 −1 4 T 0 −1 0 −1 −1 −1 −1 −2 −2 −1 −1 −1 −1 −2 −1 1 5 W −3 −3 −4 −4−2 −2 −3 −2 −2 −3 −2 −3 −1 1 −4 −3 −2 11 Y −2 −2 −2 −3 −2 −1 −2 −3 2 −1−1 −2 −1 3 −3 −2 −2 2 7 V 0 −3 −3 −3 −1 −2 −2 −3 −3 3 1 −2 1 −1 −2 −2 0−3 −1 4

Those skilled in the art appreciate that there are many establishedalgorithms available to align two amino acid sequences. The “FASTA”similarity search algorithm of Pearson and Lipman is a suitable proteinalignment method for examining the level of identity shared by an aminoacid sequence disclosed herein and the amino acid sequence of a putativeIL-22RA variant. The FASTA algorithm is described by Pearson and Lipman,Proc. Nat'l Acad. Sci. USA 85:2444 (1988), and by Pearson, Meth.Enzymol. 183:63 (1990). Briefly, FASTA first characterizes sequencesimilarity by identifying regions shared by the query sequence (e.g.,SEQ ID NO:2 or SEQ ID NO:3) and a test sequence that have either thehighest density of identities (if the ktup variable is 1) or pairs ofidentities (if ktup=2), without considering conservative amino acidsubstitutions, insertions, or deletions. The ten regions with thehighest density of identities are then rescored by comparing thesimilarity of all paired amino acids using an amino acid substitutionmatrix, and the ends of the regions are “trimmed” to include only thoseresidues that contribute to the highest score. If there are severalregions with scores greater than the “cutoff” value (calculated by apredetermined formula based upon the length of the sequence and the ktupvalue), then the trimmed initial regions are examined to determinewhether the regions can be joined to form an approximate alignment withgaps. Finally, the highest scoring regions of the two amino acidsequences are aligned using a modification of theNeedleman-Wunsch-Sellers algorithm (Needleman and Wunsch, J. Mol. Biol.48:444 (1970); Sellers, SIAM J. Appl. Math. 26:787 (1974)), which allowsfor amino acid insertions and deletions. Illustrative parameters forFASTA analysis are: ktup=1, gap opening penalty=10, gap extensionpenalty=1, and substitution matrix=BLOSUM62. These parameters can beintroduced into a FASTA program by modifying the scoring matrix file(“SMATRIX”), as explained in Appendix 2 of Pearson, Meth. Enzymol.183:63 (1990).

FASTA can also be used to determine the sequence identity of nucleicacid molecules using a ratio as disclosed above. For nucleotide sequencecomparisons, the ktup value can range between one to six, preferablyfrom three to six, most preferably three, with other parameters set asdescribed above.

The present invention includes nucleic acid molecules that encode apolypeptide having a conservative amino acid change, compared with anamino acid sequence disclosed herein. For example, variants can beobtained that contain one or more amino acid substitutions of SEQ IDNO:3, in which an alkyl amino acid is substituted for an alkyl aminoacid in a IL-22RA amino acid sequence, an aromatic amino acid issubstituted for an aromatic amino acid in a IL-22RA amino acid sequence,a sulfur-containing amino acid is substituted for a sulfur-containingamino acid in a IL-22RA amino acid sequence, a hydroxy-containing aminoacid is substituted for a hydroxy-containing amino acid in a IL-22RAamino acid sequence, an acidic amino acid is substituted for an acidicamino acid in a IL-22RA amino acid sequence, a basic amino acid issubstituted for a basic amino acid in a IL-22RA amino acid sequence, ora dibasic monocarboxylic amino acid is substituted for a dibasicmonocarboxylic amino acid in a IL-22RA amino acid sequence. Among thecommon amino acids, for example, a “conservative amino acidsubstitution” is illustrated by a substitution among amino acids withineach of the following groups: (1) glycine, alanine, valine, leucine, andisoleucine, (2) phenylalanine, tyrosine, and tryptophan, (3) serine andthreonine, (4) aspartate and glutamate, (5) glutamine and asparagine,and (6) lysine, arginine and histidine. The BLOSUM62 table is an aminoacid substitution matrix derived from about 2,000 local multiplealignments of protein sequence segments, representing highly conservedregions of more than 500 groups of related proteins (Henikoff andHenikoff, Proc. Nat'l Acad. Sci. USA 89:10915 (1992)). Accordingly, theBLOSUM62 substitution frequencies can be used to define conservativeamino acid substitutions that may be introduced into the amino acidsequences of the present invention. Although it is possible to designamino acid substitutions based solely upon chemical properties (asdiscussed above), the language “conservative amino acid substitution”preferably refers to a substitution represented by a BLOSUM62 value ofgreater than −1. For example, an amino acid substitution is conservativeif the substitution is characterized by a BLOSUM62 value of 0, 1, 2, or3. According to this system, preferred conservative amino acidsubstitutions are characterized by a BLOSUM62 value of at least 1 (e.g.,1, 2 or 3), while more preferred conservative amino acid substitutionsare characterized by a BLOSUM62 value of at least 2 (e.g., 2 or 3).Particular variants of IL-22RA are characterized by having at least 70%,at least 80%, at least 90%, at least 95% or greater than 95% such as96%, 97%, 98%, or 99% or greater sequence identity to the correspondingamino acid sequence (e.g., SEQ ID NO:3), wherein the variation in aminoacid sequence is due to one or more conservative amino acidsubstitutions.

Conservative amino acid changes in a IL-22RA gene can be introduced, forexample, by substituting nucleotides for the nucleotides recited in SEQID NO:1. Such “conservative amino acid” variants can be obtained byoligonucleotide-directed mutagenesis, linker-scanning mutagenesis,mutagenesis using the polymerase chain reaction, and the like (seeAusubel (1995); and McPherson (ed.), Directed Mutagenesis: A PracticalApproach (IRL Press 1991)). A variant IL-22RA polypeptide can beidentified by the ability to specifically bind anti-IL-22RA antibodies.

The proteins of the present invention can also comprise non-naturallyoccurring amino acid residues. Non-naturally occurring amino acidsinclude, without limitation, trans-3-methylproline, 2,4-methanoproline,cis-4-hydroxyproline, trans-4-hydroxyproline, N-methylglycine,allo-threonine, methylthreonine, hydroxyethylcysteine,hydroxyethylhomocysteine, nitroglutamine, homoglutamine, pipecolic acid,thiazolidine carboxylic acid, dehydroproline, 3- and 4-methylproline,3,3-dimethylproline, tert-leucine, norvaline, 2-azaphenylalanine,3-azaphenylalanine, 4-azaphenylalanine, and 4-fluorophenylalanine.Several methods are known in the art for incorporating non-naturallyoccurring amino acid residues into proteins. For example, an in vitrosystem can be employed wherein nonsense mutations are suppressed usingchemically aminoacylated suppressor tRNAs. Methods for synthesizingamino acids and aminoacylating tRNA are known in the art. Transcriptionand translation of plasmids containing nonsense mutations is typicallycarried out in a cell-free system comprising an E. coli S30 extract andcommercially available enzymes and other reagents. Proteins are purifiedby chromatography. See, for example, Robertson et al., J. Am. Chem. Soc.113:2722 (1991), Ellman et al., Methods Enzymol. 202:301 (1991), Chunget al., Science 259:806 (1993), and Chung et al., Proc. Nat'l Acad. Sci.USA 90:10145 (1993).

In a second method, translation is carried out in Xenopus oocytes bymicroinjection of mutated mRNA and chemically aminoacylated suppressortRNAs (Turcatti et al., J. Biol. Chem. 271:19991 (1996)). Within a thirdmethod, E. coli cells are cultured in the absence of a natural aminoacid that is to be replaced (e.g., phenylalanine) and in the presence ofthe desired non-naturally occurring amino acid(s) (e.g.,2-azaphenylalanine, 3-azaphenylalanine, 4-azaphenylalanine, or4-fluorophenylalanine). The non-naturally occurring amino acid isincorporated into the protein in place of its natural counterpart. See,Koide et al., Biochem. 33:7470 (1994). Naturally occurring amino acidresidues can be converted to non-naturally occurring species by in vitrochemical modification. Chemical modification can be combined withsite-directed mutagenesis to further expand the range of substitutions(Wynn and Richards, Protein Sci. 2:395 (1993)).

A limited number of non-conservative amino acids, amino acids that arenot encoded by the genetic code, non-naturally occurring amino acids,and unnatural amino acids may be substituted for IL-22RA amino acidresidues.

Essential amino acids in the polypeptides of the present invention canbe identified according to procedures known in the art, such assite-directed mutagenesis or alanine-scanning mutagenesis (Cunninghamand Wells, Science 244:1081 (1989), Bass et al., Proc. Nat'l Acad. Sci.USA 88:4498 (1991), Coombs and Corey, “Site-Directed Mutagenesis andProtein Engineering,” in Proteins: Analysis and Design, Angeletti (ed.),pages 259-311 (Academic Press, Inc. 1998)). In the latter technique,single alanine mutations are introduced at every residue in themolecule, and the resultant mutant molecules are tested for biologicalactivity to identify amino acid residues that are critical to theactivity of the molecule. See also, Hilton et al., J. Biol. Chem.271:4699 (1996).

Although sequence analysis can be used to further define the IL-22RAligand binding region, amino acids that play a role in IL-22RA bindingactivity (such as binding of IL-22RA to ligand IL-22, or to ananti-IL-22RA antibody) can also be determined by physical analysis ofstructure, as determined by such techniques as nuclear magneticresonance, crystallography, electron diffraction or photoaffinitylabeling, in conjunction with mutation of putative contact site aminoacids. See, for example, de Vos et al., Science 255:306 (1992), Smith etal., J. Mol. Biol. 224:899 (1992), and Wlodaver et al., FEBS Lett.309:59 (1992).

Multiple amino acid substitutions can be made and tested using knownmethods of mutagenesis and screening, such as those disclosed byReidhaar-Olson and Sauer (Science 241:53 (1988)) or Bowie and Sauer(Proc. Nat'l Acad. Sci. USA 86:2152 (1989)). Briefly, these authorsdisclose methods for simultaneously randomizing two or more positions ina polypeptide, selecting for functional polypeptide, and then sequencingthe mutagenized polypeptides to determine the spectrum of allowablesubstitutions at each position. Other methods that can be used includephage display (e.g., Lowman et al., Biochem. 30:10832 (1991), Ladner etal., U.S. Pat. No. 5,223,409, Huse, international publication No. WO92/06204, and region-directed mutagenesis (Derbyshire et al., Gene46:145 (1986), and Ner et al., DNA 7:127, (1988)). Moreover, IL-22RAlabeled with biotin or FITC can be used for expression cloning ofIL-22RA ligands.

Variants of the disclosed IL-22RA nucleotide and polypeptide sequencescan also be generated through DNA shuffling as disclosed by Stemmer,Nature 370:389 (1994), Stemmer, Proc. Nat'l Acad. Sci. USA 91:10747(1994), and international publication No. WO 97/20078. Briefly, variantDNA molecules are generated by in vitro homologous recombination byrandom fragmentation of a parent DNA followed by reassembly using PCR,resulting in randomly introduced point mutations. This technique can bemodified by using a family of parent DNA molecules, such as allelicvariants or DNA molecules from different species, to introduceadditional variability into the process. Selection or screening for thedesired activity, followed by additional iterations of mutagenesis andassay provides for rapid “evolution” of sequences by selecting fordesirable mutations while simultaneously selecting against detrimentalchanges.

Mutagenesis methods as disclosed herein can be combined withhigh-throughput, automated screening methods to detect activity ofcloned, mutagenized polypeptides in host cells. Mutagenized DNAmolecules that encode biologically active polypeptides, or polypeptidesthat bind with anti-IL-22RA antibodies, can be recovered from the hostcells and rapidly sequenced using modern equipment. These methods allowthe rapid determination of the importance of individual amino acidresidues in a polypeptide of interest, and can be applied topolypeptides of unknown structure.

The present invention also includes “functional fragments” of IL-22RApolypeptides and nucleic acid molecules encoding such functionalfragments. Routine deletion analyses of nucleic acid molecules can beperformed to obtain functional fragments of a nucleic acid molecule thatencodes a IL-22RA polypeptide. As an illustration, DNA molecules havingthe nucleotide sequence of SEQ ID NO:1 can be digested with Bal31nuclease to obtain a series of nested deletions. The fragments are theninserted into expression vectors in proper reading frame, and theexpressed polypeptides are isolated and tested for the ability to bindanti-IL-22RA antibodies. One alternative to exonuclease digestion is touse oligonucleotide-directed mutagenesis to introduce deletions or stopcodons to specify production of a desired fragment. Alternatively,particular fragments of a IL-22RA gene can be synthesized using thepolymerase chain reaction.

This general approach is exemplified by studies on the truncation ateither or both termini of interferons have been summarized byHorisberger and Di Marco, Pharmac. Ther. 66:507 (1995). Moreover,standard techniques for functional analysis of proteins are describedby, for example, Treuter et al., Molec. Gen. Genet. 240:113 (1993),Content et al., “Expression and preliminary deletion analysis of the 42kDa 2-5A synthetase induced by human interferon,” in BiologicalInterferon Systems, Proceedings of ISIR-TNO Meeting on InterferonSystems, Cantell (ed.), pages 65-72 (Nijhoff 1987), Herschman, “The EGFReceptor,” in Control of Animal Cell Proliferation, Vol. 1, Boynton etal., (eds.) pages 169-199 (Academic Press 1985), Coumailleau et al., J.Biol. Chem. 270:29270 (1995); Fukunaga et al., J. Biol. Chem. 270:25291(1995); Yamaguchi et al., Biochem. Pharmacol. 50:1295 (1995), and Meiselet al., Plant Molec. Biol. 30:1 (1996).

Analysis of the particular sequences disclosed herein provide a set ofillustrative functional fragments presented in Table 4. The nucleotidesencoding additional human IL-22RA functional variant domains describedherein, not show in Table 4, can be determined with reference to SEQ IDNO:1. Such functional fragments include for example, the followingnucleotide sequences of SEQ ID NO:1: nucleotides 85-381, 206-717, and85-717 of SEQ ID NO:1 and corresponding amino acid sequences encodedthereby as shown in SEQ ID NO:2 and SEQ ID NO:3 respectively.

TABLE 4 Amino acid residues Nucleotides IL-22RA Feature (SEQ ID NO: 2)(SEQ ID NO: 1) First Ig Domain 18-116 85-381 Second Ig Domain 125-228 206-717  Both Ig Domains 18-228 85-717

The present invention also contemplates functional fragments of aIL-22RA gene that have amino acid changes, compared with an amino acidsequence disclosed herein. A variant IL-22RA gene can be identified onthe basis of structure by determining the level of identity withdisclosed nucleotide and amino acid sequences, as discussed above. Analternative approach to identifying a variant gene on the basis ofstructure is to determine whether a nucleic acid molecule encoding apotential variant IL-22RA gene can hybridize to a nucleic acid moleculecomprising a nucleotide sequence, such as SEQ ID NO:1.

The present invention also includes using functional fragments ofIL-22RA polypeptides, antigenic epitopes, epitope-bearing portions ofIL-22RA polypeptides, and nucleic acid molecules that encode suchfunctional fragments, antigenic epitopes, epitope-bearing portions ofIL-22RA polypeptides. Such fragments are used to generate polypeptidesfor use in generating antibodies and binding partners that bind, block,inhibit, reduce, antagonize or neutralize activity of IL-22 or bothIL-20 and IL-22. A “functional” IL-22RA polypeptide or fragment thereofas defined herein is characterized by its ability to block, inhibit,reduce, antagonize or neutralize IL-20 or IL-22 inflammatory,proliferative or differentiating activity, by its ability to induce orinhibit specialized cell functions, or by its ability to bindspecifically to an anti-IL-22RA antibody, cell, IL-20 or IL-22. Aspreviously described herein, IL-22RA is characterized by a class IIcytokine receptor structure and domains as described herein. Thus, thepresent invention further contemplates using fusion proteinsencompassing: (a) polypeptide molecules comprising one or more of thedomains described above; and (b) functional fragments comprising one ormore of these domains. The other polypeptide portion of the fusionprotein may be contributed by another class II cytokine receptor, suchas IL-10R, IL-13R, IL-20RA, IL-20RB, IL-10RB (CRF2-4), IL-22RA2, or by anon-native and/or an unrelated secretory signal peptide that facilitatessecretion of the fusion protein.

The present invention also provides polypeptide fragments or peptidescomprising an epitope-bearing portion of a IL-22RA polypeptide describedherein. Such fragments or peptides may comprise an “immunogenicepitope,” which is a part of a protein that elicits an antibody responsewhen the entire protein is used as an immunogen. Immunogenicepitope-bearing peptides can be identified using standard methods (see,for example, Geysen et al., Proc. Nat'l Acad. Sci. USA 81:3998 (1983)).

In contrast, polypeptide fragments or peptides may comprise an“antigenic epitope,” which is a region of a protein molecule to which anantibody can specifically bind. Certain epitopes consist of a linear orcontiguous stretch of amino acids, and the antigenicity of such anepitope is not disrupted by denaturing agents. It is known in the artthat relatively short synthetic peptides that can mimic epitopes of aprotein can be used to stimulate the production of antibodies againstthe protein (see, for example, Sutcliffe et al., Science 219:660(1983)). Accordingly, antigenic epitope-bearing peptides, antigenicpeptides, epitopes, and polypeptides of the present invention are usefulto raise antibodies that bind with the polypeptides described herein, aswell as to identify and screen anti-IL-22RA monoclonal antibodies thatare neutralizing, and that may bind, block, inhibit, reduce, antagonizeor neutralize the activity of IL-22 and IL-20 (individually ortogether). Such neutralizing monoclonal antibodies of the presentinvention can bind to an IL-22RA antigenic epitope. Hopp/Woodshydrophilicity profiles can be used to determine regions that have themost antigenic potential within SEQ ID NO:3 (Hopp et al., Proc. Natl.Acad. Sci. 78:3824-3828, 1981; Hopp, J. Immun. Meth. 88:1-18, 1986 andTriquier et al., Protein Engineering 11:153-169, 1998). The profile isbased on a sliding six-residue window. Buried G, S, and T residues andexposed H, Y, and W residues were ignored. In IL-22RA these regions canbe determined by one of skill in the art. Moreover, IL-22RA antigenicepitopes within SEQ ID NO:3 as predicted by a Jameson-Wolf plot, e.g.,using DNASTAR Protean program (DNASTAR, Inc., Madison, Wis.) serve aspreferred antigenic epitopes, and can be determined by one of skill inthe art. Such antigenic epitopes include (1) amino acid residues 1 (Pro)to 6 (Asp) of SEQ ID NO:3; (2) amino acid residues 26 (Ser) to 32 (Pro)of SEQ ID NO:3; (3) amino acid residues 41 (Lys) to 47 (Asp) of SEQ IDNO:3; (4) amino acid residues 49 (Val) to 62 (Cys) of SEQ ID NO:3; (5)amino acid residues 41 (Lys) to 62 (Cys) of SEQ ID NO:3; (6) amino acidresidues 84 (Ala) to 97 (Ser) of SEQ ID NO:3; (7) amino acid residues103 (Thr) to 108 (Asp) of SEQ ID NO:3; (8) amino acid residues 130 (Arg)to 135 (His) of SEQ ID NO:3; (9) amino acid residues 164 (Gly) to 166(Lys) of SEQ ID NO:3; (10) amino acid residues 175 (Tyr) to 179 (Glu) ofSEQ ID NO:3; (11) amino acid residues 193 (Lys) to 196 (Ala) of SEQ IDNO:3; (12) amino acid residues 203 (Lys) to 209 (Thr) of SEQ ID NO:3.Additional epitopes include the following peptides are potentiallygenerated from non-reduced full-length human IL-22RA cleaved with CnBr:peptide 6 (SEQ ID NO:56), peptide 7 (SEQ ID NO:57); peptide 8 (SEQ IDNO:58); peptide 9 (SEQ ID NO:59); peptide 10 (SEQ ID NO:60); and peptide11 (SEQ ID NO:61). Cysteines are disulfide-bonded, which results in apossible link between peptides 7 (SEQ ID NO:57) and 10 (SEQ ID NO:60.Specifically, SEQ ID NO:56 corresponds to amino acid residues 1 (Pro) to92 (Met) of SEQ ID NO:3; SEQ ID NO:57 corresponds to amino acid residues93 (Thr) to 120 (Met) of SEQ ID NO:3, SEQ ID NO:58 corresponds to aminoacid residues 121 (Ile) to 160 (Met) of SEQ ID NO:3, SEQ ID NO:59corresponds to amino acid residues 161 (His) to 185 (Met) of SEQ IDNO:3, SEQ ID NO:60 corresponds to amino acid residues 186 (Ile) to 199(Met) of SEQ ID NO:3 and SEQ ID NO:61 corresponds to amino acid residues200 (Cys) to 211 (Thr) of SEQ ID NO:3. In addition, residues of SEQ IDNO:2 (and corresponding residues of SEQ ID NO:3) that are important toligand-receptor binding comprise Tyr-60, and Phe-164, Tyr-93, Arg-112,Lys-210, and Glu-211 of SEQ ID NO:2 and (and corresponding residues ofSEQ ID NO:3). Moreover, primary residues of SEQ ID NO:2 (andcorresponding residues of SEQ ID NO:3) that are important to directligand-receptor binding comprise Tyr-60, and Phe-164 of SEQ ID NO:2 (andcorresponding residues of SEQ ID NO:3), and secondary residues compriseresidues Tyr-93, Arg-112, Lys-210, and Glu-211 of SEQ ID NO:2 and (andcorresponding residues of SEQ ID NO:3). In preferred embodiments,antigenic epitopes to which neutralizing antibodies of the presentinvention bind would contain residues of SEQ ID NO:2 (and correspondingresidues of SEQ ID NO:3) that are important to ligand-receptor binding,for example, with IL-22RA and IL-20 or IL-22 (individually or together).

Antigenic epitope-bearing peptides and polypeptides can contain at leastfour to ten amino acids, at least ten to fifteen amino acids, or about15 to about 30 amino acids of an amino acid sequence disclosed herein.Such epitope-bearing peptides and polypeptides can be produced byfragmenting a IL-22RA polypeptide, or by chemical peptide synthesis, asdescribed herein. Moreover, epitopes can be selected by phage display ofrandom peptide libraries (see, for example, Lane and Stephen, Curr.Opin. Immunol. 5:268 (1993), and Cortese et al., Curr. Opin. Biotechnol.7:616 (1996)). Standard methods for identifying epitopes and producingantibodies from small peptides that comprise an epitope are described,for example, by Mole, “Epitope Mapping,” in Methods in MolecularBiology, Vol. 10, Manson (ed.), pages 105-116 (The Humana Press, Inc.1992), Price, “Production and Characterization of SyntheticPeptide-Derived Antibodies,” in Monoclonal Antibodies: Production,Engineering, and Clinical Application, Ritter and Ladyman (eds.), pages60-84 (Cambridge University Press 1995), and Coligan et al. (eds.),Current Protocols in Immunology, pages 9.3.1-9.3.5 and pages9.4.1-9.4.11 (John Wiley & Sons 1997).

For any IL-22RA polypeptide, including variants and fusion proteins, oneof ordinary skill in the art can readily generate a fully degeneratepolynucleotide sequence encoding that variant using the information setforth in Tables 1 and 2 above. Moreover, those of skill in the art canuse standard software to devise IL-22RA variants based upon thenucleotide and amino acid sequences described herein.

5. Production of IL-22RA Polypeptides

The polypeptides of the present invention, including full-lengthpolypeptides; soluble monomeric, homodimeric, heterodimeric andmultimeric receptors; full-length receptors; receptor fragments (e.g.ligand-binding fragments and antigenic epitopes), functional fragments,and fusion proteins, can be produced in recombinant host cells followingconventional techniques. To express a IL-22RA gene, a nucleic acidmolecule encoding the polypeptide must be operably linked to regulatorysequences that control transcriptional expression in an expressionvector and then, introduced into a host cell. In addition totranscriptional regulatory sequences, such as promoters and enhancers,expression vectors can include translational regulatory sequences and amarker gene which is suitable for selection of cells that carry theexpression vector.

Expression vectors that are suitable for production of a foreign proteinin eukaryotic cells typically contain (1) prokaryotic DNA elementscoding for a bacterial replication origin and an antibiotic resistancemarker to provide for the growth and selection of the expression vectorin a bacterial host; (2) eukaryotic DNA elements that control initiationof transcription, such as a promoter; and (3) DNA elements that controlthe processing of transcripts, such as a transcriptiontermination/polyadenylation sequence. As discussed above, expressionvectors can also include nucleotide sequences encoding a secretorysequence that directs the heterologous polypeptide into the secretorypathway of a host cell. For example, an IL-22RA expression vector maycomprise a IL-22RA gene and a secretory sequence derived from anysecreted gene.

IL-22RA proteins of the present invention may be expressed in mammaliancells. Examples of suitable mammalian host cells include African greenmonkey kidney cells (Vero; ATCC CRL 1587), human embryonic kidney cells(293-HEK; ATCC CRL 1573), baby hamster kidney cells (BHK-21, BHK-570;ATCC CRL 8544, ATCC CRL 10314), canine kidney cells (MDCK; ATCC CCL 34),Chinese hamster ovary cells (CHO-K1; ATCC CCL61; CHO DG44 (Chasin etal., Som. Cell. Molec. Genet. 12:555, 1986)), rat pituitary cells (GH1;ATCC CCL82), HeLa S3 cells (ATCC CCL2.2), rat hepatoma cells (H-4-II-E;ATCC CRL 1548) SV40-transformed monkey kidney cells (COS-1; ATCC CRL1650) and murine embryonic cells (NIH-3T3; ATCC CRL 1658).

For a mammalian host, the transcriptional and translational regulatorysignals may be derived from mammalian viral sources, for example,adenovirus, bovine papilloma virus, simian virus, or the like, in whichthe regulatory signals are associated with a particular gene which has ahigh level of expression. Suitable transcriptional and translationalregulatory sequences also can be obtained from mammalian genes, forexample, actin, collagen, myosin, and metallothionein genes.

Transcriptional regulatory sequences include a promoter regionsufficient to direct the initiation of RNA synthesis. Suitableeukaryotic promoters include the promoter of the mouse metallothionein Igene (Hamer et al., J. Molec. Appl. Genet. 1:273 (1982)), the TKpromoter of Herpes virus (McKnight, Cell 31:355 (1982)), the SV40 earlypromoter (Benoist et al., Nature 290:304 (1981)), the Rous sarcoma viruspromoter (Gorman et al., Proc. Nat'l Acad. Sci. USA 79:6777 (1982)), thecytomegalovirus promoter (Foecking et al., Gene 45:101 (1980)), and themouse mammary tumor virus promoter (see, generally, Etcheverry,“Expression of Engineered Proteins in Mammalian Cell Culture,” inProtein Engineering: Principles and Practice, Cleland et al. (eds.),pages 163-181 (John Wiley & Sons, Inc. 1996)).

Alternatively, a prokaryotic promoter, such as the bacteriophage T3 RNApolymerase promoter, can be used to control IL-22RA gene expression inmammalian cells if the prokaryotic promoter is regulated by a eukaryoticpromoter (Zhou et al., Mol. Cell. Biol. 10:4529 (1990), and Kaufman etal., Nucl. Acids Res. 19:4485 (1991)).

In certain embodiments, a DNA sequence encoding a IL-22RA solublereceptor polypeptide, or a fragment of IL-22RA polypeptide is operablylinked to other genetic elements required for its expression, generallyincluding a transcription promoter and terminator, within an expressionvector. The vector will also commonly contain one or more selectablemarkers and one or more origins of replication, although those skilledin the art will recognize that within certain systems selectable markersmay be provided on separate vectors, and replication of the exogenousDNA may be provided by integration into the host cell genome. Selectionof promoters, terminators, selectable markers, vectors and otherelements is a matter of routine design within the level of ordinaryskill in the art. Many such elements are described in the literature andare available through commercial suppliers. Multiple components of asoluble receptor complex can be co-transfected on individual expressionvectors or be contained in a single expression vector. Such techniquesof expressing multiple components of protein complexes are well known inthe art.

An expression vector can be introduced into host cells using a varietyof standard techniques including calcium phosphate transfection,liposome-mediated transfection, microprojectile-mediated delivery,electroporation, and the like. The transfected cells can be selected andpropagated to provide recombinant host cells that comprise theexpression vector stably integrated in the host cell genome. Techniquesfor introducing vectors into eukaryotic cells and techniques forselecting such stable transformants using a dominant selectable markerare described, for example, by Ausubel (1995) and by Murray (ed.), GeneTransfer and Expression Protocols (Humana Press 1991).

For example, one suitable selectable marker is a gene that providesresistance to the antibiotic neomycin. In this case, selection iscarried out in the presence of a neomycin-type drug, such as G-418 orthe like. Selection systems can also be used to increase the expressionlevel of the gene of interest, a process referred to as “amplification.”Amplification is carried out by culturing transfectants in the presenceof a low level of the selective agent and then increasing the amount ofselective agent to select for cells that produce high levels of theproducts of the introduced genes. A suitable amplifiable selectablemarker is dihydrofolate reductase (DHFR), which confers resistance tomethotrexate. Other drug resistance genes (e.g., hygromycin resistance,multi-drug resistance, puromycin acetyltransferase) can also be used.Alternatively, markers that introduce an altered phenotype, such asgreen fluorescent protein, or cell surface proteins such as CD4, CD8,Class I MHC, placental alkaline phosphatase may be used to sorttransfected cells from untransfected cells by such means as FACS sortingor magnetic bead separation technology.

IL-22RA polypeptides can also be produced by cultured mammalian cellsusing a viral delivery system. Exemplary viruses for this purposeinclude adenovirus, retroviruses, herpesvirus, vaccinia virus andadeno-associated virus (AAV). Adenovirus, a double-stranded DNA virus,is currently the best studied gene transfer vector for delivery ofheterologous nucleic acid (for a review, see Becker et al., Meth. CellBiol. 43:161 (1994), and Douglas and Curiel, Science & Medicine 4:44(1997)). Advantages of the adenovirus system include the accommodationof relatively large DNA inserts, the ability to grow to high-titer, theability to infect a broad range of mammalian cell types, and flexibilitythat allows use with a large number of available vectors containingdifferent promoters.

By deleting portions of the adenovirus genome, larger inserts (up to 7kb) of heterologous DNA can be accommodated. These inserts can beincorporated into the viral DNA by direct ligation or by homologousrecombination with a co-transfected plasmid. An option is to delete theessential E1 gene from the viral vector, which results in the inabilityto replicate unless the E1 gene is provided by the host cell. Adenovirusvector-infected human 293 cells (ATCC Nos. CRL-1573, 45504, 45505), forexample, can be grown as adherent cells or in suspension culture atrelatively high cell density to produce significant amounts of protein(see Garnier et al., Cytotechnol. 15:145 (1994)).

IL-22RA can also be expressed in other higher eukaryotic cells, such asavian, fungal, insect, yeast, or plant cells. The baculovirus systemprovides an efficient means to introduce cloned IL-22RA genes intoinsect cells. Suitable expression vectors are based upon the Autographacalifornica multiple nuclear polyhedrosis virus (AcMNPV), and containwell-known promoters such as Drosophila heat shock protein (hsp) 70promoter, Autographa californica nuclear polyhedrosis virusimmediate-early gene promoter (ie-1) and the delayed early 39K promoter,baculovirus p10 promoter, and the Drosophila metallothionein promoter. Asecond method of making recombinant baculovirus utilizes atransposon-based system described by Luckow (Luckow, et al., J. Virol.67:4566 (1993)). This system, which utilizes transfer vectors, is soldin the BAC-to-BAC kit (Life Technologies, Rockville, Md.). This systemutilizes a transfer vector, PFASTBAC (Life Technologies) containing aTn7 transposon to move the DNA encoding the IL-22RA polypeptide into abaculovirus genome maintained in E. coli as a large plasmid called a“bacmid.” See, Hill-Perkins and Possee, J. Gen. Virol. 71:971 (1990),Bonning, et al., J. Gen. Virol. 75:1551 (1994), and Chazenbalk, andRapoport, J. Biol. Chem. 270:1543 (1995). In addition, transfer vectorscan include an in-frame fusion with DNA encoding an epitope tag at theC- or N-terminus of the expressed IL-22RA polypeptide, for example, aGlu-Glu epitope tag (Grussenmeyer et al., Proc. Nat'l Acad. Sci. 82:7952(1985)). Using a technique known in the art, a transfer vectorcontaining a IL-22RA gene is transformed into E. coli, and screened forbacmids which contain an interrupted lacZ gene indicative of recombinantbaculovirus. The bacmid DNA containing the recombinant baculovirusgenome is then isolated using common techniques.

The illustrative PFASTBAC vector can be modified to a considerabledegree. For example, the polyhedrin promoter can be removed andsubstituted with the baculovirus basic protein promoter (also known asPcor, p6.9 or MP promoter) which is expressed earlier in the baculovirusinfection, and has been shown to be advantageous for expressing secretedproteins (see, for example, Hill-Perkins and Possee, J. Gen. Virol.71:971 (1990), Bonning, et al., J. Gen. Virol. 75:1551 (1994), andChazenbalk and Rapoport, J. Biol. Chem. 270:1543 (1995). In suchtransfer vector constructs, a short or long version of the basic proteinpromoter can be used. Moreover, transfer vectors can be constructedwhich replace the native IL-22RA secretory signal sequences withsecretory signal sequences derived from insect proteins. For example, asecretory signal sequence from Ecdysteroid Glucosyltransferase (EGT),honey bee Melittin (Invitrogen Corporation; Carlsbad, Calif.), orbaculovirus gp67 (PharMingen: San Diego, Calif.) can be used inconstructs to replace the native IL-22RA secretory signal sequence.

The recombinant virus or bacmid is used to transfect host cells.Suitable insect host cells include cell lines derived from IPLB-Sf-21, aSpodoptera frugiperda pupal ovarian cell line, such as Sf9 (ATCC CRL1711), Sf21AE, and Sf21 (Invitrogen Corporation; San Diego, Calif.), aswell as Drosophila Schneider-2 cells, and the HIGH FIVEO cell line(Invitrogen) derived from Trichoplusia ni (U.S. Pat. No. 5,300,435).Commercially available serum-free media can be used to grow and tomaintain the cells. Suitable media are Sf900 II™ (Life Technologies) orESF 921™ (Expression Systems) for the Sf9 cells; and Ex-cellO405™ (JRHBiosciences, Lenexa, Kans.) or Express FiveO™ (Life Technologies) forthe T. ni cells. When recombinant virus is used, the cells are typicallygrown up from an inoculation density of approximately 2-5×10⁵ cells to adensity of 1-2×10⁶ cells at which time a recombinant viral stock isadded at a multiplicity of infection (MOI) of 0.1 to 10, more typicallynear 3.

Established techniques for producing recombinant proteins in baculovirussystems are provided by Bailey et al., “Manipulation of BaculovirusVectors,” in Methods in Molecular Biology, Volume 7: Gene Transfer andExpression Protocols, Murray (ed.), pages 147-168 (The Humana Press,Inc. 1991), by Patel et al., “The baculovirus expression system,” in DNACloning 2: Expression Systems, 2nd Edition, Glover et al. (eds.), pages205-244 (Oxford University Press 1995), by Ausubel (1995) at pages 16-37to 16-57, by Richardson (ed.), Baculovirus Expression Protocols (TheHumana Press, Inc. 1995), and by Lucknow, “Insect Cell ExpressionTechnology,” in Protein Engineering: Principles and Practice, Cleland etal. (eds.), pages 183-218 (John Wiley & Sons, Inc. 1996).

Fungal cells, including yeast cells, can also be used to express thegenes described herein. Yeast species of particular interest in thisregard include Saccharomyces cerevisiae, Pichia pastoris, and Pichiamethanotica. Suitable promoters for expression in yeast includepromoters from GAL1 (galactose), PGK (phosphoglycerate kinase), ADH(alcohol dehydrogenase), AOX1 (alcohol oxidase), HIS4 (histidinoldehydrogenase), and the like. Many yeast cloning vectors have beendesigned and are readily available. These vectors include YIp-basedvectors, such as YIp5, YRp vectors, such as YRp17, YEp vectors such asYEp13 and YCp vectors, such as YCp19. Methods for transforming S.cerevisiae cells with exogenous DNA and producing recombinantpolypeptides therefrom are disclosed by, for example, Kawasaki, U.S.Pat. No. 4,599,311, Kawasaki et al., U.S. Pat. No. 4,931,373, Brake,U.S. Pat. No. 4,870,008, Welch et al., U.S. Pat. No. 5,037,743, andMurray et al., U.S. Pat. No. 4,845,075. Transformed cells are selectedby phenotype determined by the selectable marker, commonly drugresistance or the ability to grow in the absence of a particularnutrient (e.g., leucine). A suitable vector system for use inSaccharomyces cerevisiae is the POT1 vector system disclosed by Kawasakiet al. (U.S. Pat. No. 4,931,373), which allows transformed cells to beselected by growth in glucose-containing media. Additional suitablepromoters and terminators for use in yeast include those from glycolyticenzyme genes (see, e.g., Kawasaki, U.S. Pat. No. 4,599,311, Kingsman etal., U.S. Pat. No. 4,615,974, and Bitter, U.S. Pat. No. 4,977,092) andalcohol dehydrogenase genes. See also U.S. Pat. Nos. 4,990,446,5,063,154, 5,139,936, and 4,661,454.

Transformation systems for other yeasts, including Hansenula polymorpha,Schizosaccharomyces pombe, Kluyveromyces lactis, Kluyveromyces fragilis,Ustilago maydis, Pichia pastoris, Pichia methanolica, Pichiaguillermondii and Candida maltosa are known in the art. See, forexample, Gleeson et al., J. Gen. Microbiol. 132:3459 (1986), and Cregg,U.S. Pat. No. 4,882,279. Aspergillus cells may be utilized according tothe methods of McKnight et al., U.S. Pat. No. 4,935,349. Methods fortransforming Acremonium chrysogenum are disclosed by Sumino et al., U.S.Pat. No. 5,162,228. Methods for transforming Neurospora are disclosed byLambowitz, U.S. Pat. No. 4,486,533.

For example, the use of Pichia methanolica as host for the production ofrecombinant proteins is disclosed by Raymond, U.S. Pat. No. 5,716,808,Raymond, U.S. Pat. No. 5,736,383, Raymond et al., Yeast 14:11-23 (1998),and in international publication Nos. WO 97/17450, WO 97/17451, WO98/02536, and WO 98/02565. DNA molecules for use in transforming P.methanolica will commonly be prepared as double-stranded, circularplasmids, which are preferably linearized prior to transformation. Forpolypeptide production in P. methanolica, the promoter and terminator inthe plasmid can be that of a P. methanolica gene, such as a P.methanolica alcohol utilization gene (AUG1 or AUG2). Other usefulpromoters include those of the dihydroxyacetone synthase (DHAS), formatedehydrogenase (FMD), and catalase (CAT) genes. To facilitate integrationof the DNA into the host chromosome, it is preferred to have the entireexpression segment of the plasmid flanked at both ends by host DNAsequences. A suitable selectable marker for use in Pichia methanolica isa P. methanolica ADE2 gene, which encodesphosphoribosyl-5-aminoimidazole carboxylase (AIRC; EC 4.1.1.21), andwhich allows ade2 host cells to grow in the absence of adenine. Forlarge-scale, industrial processes where it is desirable to minimize theuse of methanol, host cells can be used in which both methanolutilization genes (AUG1 and AUG2) are deleted. For production ofsecreted proteins, host cells can be deficient in vacuolar proteasegenes (PEP4 and PRB1). Electroporation is used to facilitate theintroduction of a plasmid containing DNA encoding a polypeptide ofinterest into P. methanolica cells. P. methanolica cells can betransformed by electroporation using an exponentially decaying, pulsedelectric field having a field strength of from 2.5 to 4.5 kV/cm,preferably about 3.75 kV/cm, and a time constant (t) of from 1 to 40milliseconds, most preferably about 20 milliseconds.

Expression vectors can also be introduced into plant protoplasts, intactplant tissues, or isolated plant cells. Methods for introducingexpression vectors into plant tissue include the direct infection orco-cultivation of plant tissue with Agrobacterium tumefaciens,microprojectile-mediated delivery, DNA injection, electroporation, andthe like. See, for example, Horsch et al., Science 227:1229 (1985),Klein et al., Biotechnology 10:268 (1992), and Miki et al., “Proceduresfor Introducing Foreign DNA into Plants,” in Methods in Plant MolecularBiology and Biotechnology, Glick et al. (eds.), pages 67-88 (CRC Press,1993).

Alternatively, IL-22RA genes can be expressed in prokaryotic host cells.Suitable promoters that can be used to express IL-22RA polypeptides in aprokaryotic host are well-known to those of skill in the art and includepromoters capable of recognizing the T4, T3, Sp6 and T7 polymerases, theP_(R) and P_(L) promoters of bacteriophage lambda, the trp, recA, heatshock, lacUV5, tac, lpp-lacSpr, phoA, and lacZ promoters of E. coli,promoters of B. subtilis, the promoters of the bacteriophages ofBacillus, Streptomyces promoters, the int promoter of bacteriophagelambda, the bla promoter of pBR322, and the CAT promoter of thechloramphenicol acetyl transferase gene. Prokaryotic promoters have beenreviewed by Glick, J. Ind. Microbiol. 1:277 (1987), Watson et al.,Molecular Biology of the Gene, 4th Ed. (Benjamin Cummins 1987), and byAusubel et al. (1995).

Suitable prokaryotic hosts include E. coli and Bacillus subtilus.Suitable strains of E. coli include BL21(DE3), BL21(DE3)pLysS,BL21(DE3)pLysE, DH1, DH4I, DH5, DH5I, DH5IF′, DH5IMCR, DH10B, DH10B/p3,DH11S, C600, HB101, JM101, JM105, JM109, JM110, K38, RR1, Y1088, Y1089,CSH18, ER1451, and ER1647 (see, for example, Brown (ed.), MolecularBiology Labfax (Academic Press 1991)). Suitable strains of Bacillussubtilus include BR151, YB886, MI119, MI120, and B170 (see, for example,Hardy, “Bacillus Cloning Methods,” in DNA Cloning: A Practical Approach,Glover (ed.) (IRL Press 1985)).

When expressing a IL-22RA polypeptide in bacteria such as E. coli, thepolypeptide may be retained in the cytoplasm, typically as insolublegranules, or may be directed to the periplasmic space by a bacterialsecretion sequence. In the former case, the cells are lysed, and thegranules are recovered and denatured using, for example, guanidineisothiocyanate or urea. The denatured polypeptide can then be refoldedand dimerized by diluting the denaturant, such as by dialysis against asolution of urea and a combination of reduced and oxidized glutathione,followed by dialysis against a buffered saline solution. In the lattercase, the polypeptide can be recovered from the periplasmic space in asoluble and functional form by disrupting the cells (by, for example,sonication or osmotic shock) to release the contents of the periplasmicspace and recovering the protein, thereby obviating the need fordenaturation and refolding.

Methods for expressing proteins in prokaryotic hosts are well-known tothose of skill in the art (see, for example, Williams et al.,“Expression of foreign proteins in E. coli using plasmid vectors andpurification of specific polyclonal antibodies,” in DNA Cloning 2:Expression Systems, 2nd Edition, Glover et al. (eds.), page 15 (OxfordUniversity Press 1995), Ward et al., “Genetic Manipulation andExpression of Antibodies,” in Monoclonal Antibodies: Principles andApplications, page 137 (Wiley-Liss, Inc. 1995), and Georgiou,“Expression of Proteins in Bacteria,” in Protein Engineering: Principlesand Practice, Cleland et al. (eds.), page 101 (John Wiley & Sons, Inc.1996)).

Standard methods for introducing expression vectors into bacterial,yeast, insect, and plant cells are provided, for example, by Ausubel(1995).

General methods for expressing and recovering foreign protein producedby a mammalian cell system are provided by, for example, Etcheverry,“Expression of Engineered Proteins in Mammalian Cell Culture,” inProtein Engineering: Principles and Practice, Cleland et al. (eds.),pages 163 (Wiley-Liss, Inc. 1996). Standard techniques for recoveringprotein produced by a bacterial system is provided by, for example,Grisshammer et al., “Purification of over-produced proteins from E. colicells,” in DNA Cloning 2: Expression Systems, 2nd Edition, Glover et al.(eds.), pages 59-92 (Oxford University Press 1995). Established methodsfor isolating recombinant proteins from a baculovirus system aredescribed by Richardson (ed.), Baculovirus Expression Protocols (TheHumana Press, Inc. 1995).

As an alternative, polypeptides of the present invention can besynthesized by exclusive solid phase synthesis, partial solid phasemethods, fragment condensation or classical solution synthesis. Thesesynthesis methods are well-known to those of skill in the art (see, forexample, Merrifield, J. Am. Chem. Soc. 85:2149 (1963), Stewart et al.,“Solid Phase Peptide Synthesis” (2nd Edition), (Pierce Chemical Co.1984), Bayer and Rapp, Chem. Pept. Prot. 3:3 (1986), Atherton et al.,Solid Phase Peptide Synthesis: A Practical Approach (IRL Press 1989),Fields and Colowick, “Solid-Phase Peptide Synthesis,” Methods inEnzymology Volume 289 (Academic Press 1997), and Lloyd-Williams et al.,Chemical Approaches to the Synthesis of Peptides and Proteins (CRCPress, Inc. 1997)). Variations in total chemical synthesis strategies,such as “native chemical ligation” and “expressed protein ligation” arealso standard (see, for example, Dawson et al., Science 266:776 (1994),Hackeng et al., Proc. Nat'l Acad. Sci. USA 94:7845 (1997), Dawson,Methods Enzymol. 287: 34 (1997), Muir et al, Proc. Nat'l Acad. Sci. USA95:6705 (1998), and Severinov and Muir, J. Biol. Chem. 273:16205(1998)).

Peptides and polypeptides of the present invention comprise at leastsix, at least nine, or at least 15 contiguous amino acid residues of SEQID NO:3. As an illustration, polypeptides can comprise at least six, atleast nine, or at least 15 contiguous amino acid residues of SEQ IDNO:3. Within certain embodiments of the invention, the polypeptidescomprise 20, 30, 40, 50, 100, or more contiguous residues of these aminoacid sequences. Nucleic acid molecules encoding such peptides andpolypeptides are useful as polymerase chain reaction primers and probes.

Moreover, IL-22RA polypeptides and fragments thereof can be expressed asmonomers, homodimers, heterodimers, or multimers within highereukaryotic cells. Such cells can be used to produce IL-22RA monomeric,homodimeric, heterodimeric and multimeric receptor polypeptides thatcomprise at least one IL-22RA polypeptide (“IL-22RA-comprisingreceptors” or “IL-22RA-comprising receptor polypeptides”), or can beused as assay cells in screening systems. Within one aspect of thepresent invention, a polypeptide of the present invention comprising theIL-22RA extracellular domain is produced by a cultured cell, and thecell is used to screen for ligands for the receptor, including thenatural ligand, IL-22, as well as agonists and antagonists of thenatural ligand. To summarize this approach, a cDNA or gene encoding thereceptor is combined with other genetic elements required for itsexpression (e.g., a transcription promoter), and the resultingexpression vector is inserted into a host cell. Cells that express theDNA and produce functional receptor are selected and used within avariety of screening systems. Each component of the monomeric,homodimeric, heterodimeric and multimeric receptor complex can beexpressed in the same cell. Moreover, the components of the monomeric,homodimeric, heterodimeric and multimeric receptor complex can also befused to a transmembrane domain or other membrane fusion moiety to allowcomplex assembly and screening of transfectants as described above.

To assay the IL-20 and IL-22 antagonist polyepeptides and antibodies ofthe present invention, mammalian cells suitable for use in expressingIL-22RA-comprising receptors or other receptors known to bind IL-20 orIL-22 (e.g., cells expressing IL-22RA/CRF2-4; and IL-20RA, IL-20RB,IL-22RA/IL-20RB, or IL-20RA/IL-20RB) and transducing a receptor-mediatedsignal include cells that express other receptor subunits that may forma functional complex with IL-22RA (or IL-20RA). These subunits mayinclude those of the interferon receptor family or of other class II orclass I cytokine receptors, e.g., CRF2-4 (Genbank Accession No. Z17227),IL-10R (Genbank Accession Nos. U00672 and NM_(—)001558), IL-22RA(commonly owned U.S. Pat. No. 5,965,704), zcytor7 (IL-20RA) (commonlyowned U.S. Pat. No. 5,945,511), IL-20RA/IL-20RB (WIPO Publication No. WO01/46232), and IL-9R. It is also preferred to use a cell from the samespecies as the receptor to be expressed. Within a preferred embodiment,the cell is dependent upon an exogenously supplied hematopoietic growthfactor for its proliferation. Preferred cell lines of this type are thehuman TF-1 cell line (ATCC number CRL-2003) and the AML-193 cell line(ATCC number CRL-9589), which are GM-CSF-dependent human leukemic celllines and BaF3 (Palacios and Steinmetz, Cell 41: 727-734, (1985)) whichis an IL-3 dependent murine pre-B cell line. Other cell lines includeBHK, COS-1 and CHO cells. Suitable host cells can be engineered toproduce the necessary receptor subunits or other cellular componentneeded for the desired cellular response. This approach is advantageousbecause cell lines can be engineered to express receptor subunits fromany species, thereby overcoming potential limitations arising fromspecies specificity. Species orthologs of the human receptor cDNA can becloned and used within cell lines from the same species, such as a mousecDNA in the BaF3 cell line. Cell lines that are dependent upon onehematopoietic growth factor, such as GM-CSF or IL-3, can thus beengineered to become dependent upon another cytokine that acts throughthe IL-22RA receptor, such as IL-22.

Cells expressing functional receptor are used within screening assays. Avariety of suitable assays are known in the art. These assays are basedon the detection of a biological response in a target cell. One suchassay is a cell proliferation assay. Cells are cultured in the presenceor absence of a test compound, and cell proliferation is detected by,for example, measuring incorporation of tritiated thymidine or bycolorimetric assay based on the metabolic breakdown of3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT)(Mosman, J. Immunol. Meth. 65: 55-63, (1983)). An alternative assayformat uses cells that are further engineered to express a reportergene. The reporter gene is linked to a promoter element that isresponsive to the receptor-linked pathway, and the assay detectsactivation of transcription of the reporter gene. A preferred promoterelement in this regard is a serum response element, or SRE. See, e.g.,Shaw et al., Cell 56:563-572, (1989). A preferred such reporter gene isa luciferase gene (de Wet et al., Mol. Cell. Biol. 7:725, (1987)).Expression of the luciferase gene is detected by luminescence usingmethods known in the art (e.g., Baumgartner et al., J. Biol. Chem.269:29094-29101, (1994); Schenborn and Goiffin, Promega _(—) Notes41:11, 1993). Luciferase activity assay kits are commercially availablefrom, for example, Promega Corp., Madison, Wis. Target cell lines ofthis type can be used to screen libraries of chemicals, cell-conditionedculture media, fungal broths, soil samples, water samples, and the like.For example, a bank of cell-conditioned media samples can be assayed ona target cell to identify cells that produce ligand. Positive cells arethen used to produce a cDNA library in a mammalian expression vector,which is divided into pools, transfected into host cells, and expressed.Media samples from the transfected cells are then assayed, withsubsequent division of pools, re-transfection, subculturing, andre-assay of positive cells to isolate a cloned cDNA encoding the ligand.

Several IL-20 responsive cell lines are known in the art or can beconstructed, for example, the Baf3/DIRS1/cytoR11 cell line (WIPOPublication No. WO 02/072607). Moreover several IL-22 responsive celllines are known (Dumontier et al., J. Immunol. 164:1814-1819, 2000;Dumoutier, L. et al., Proc. Nat'l. Acad. Sci. 97:10144-10149, 2000; XieM H et al., J. Biol. Chem. 275: 31335-31339, 2000; Kotenko S V et al.,J. Biol. Chem. 276:2725-2732, 2001), as well as those that express theIL-22 receptor subunit IL-22RA. For example, the following cells areresponsive to IL-22: TK-10 (Xie M H et al., supra.) (human renalcarcinoma); SW480 (ATCC No. CCL-228) (human colon adenocarcinoma); HepG2(ATCC No. HB-8065) (human hepatoma); PC12 (ATCC No. CRL-1721) (murineneuronal cell model; rat pheochromocytoma); and MES13 (ATCC No.CRL-1927) (murine kidney mesangial cell line). In addition, some celllines express IL-22RA (IL-22 receptor) are also candidates forresponsive cell lines to IL-22: A549 (ATCC No. CCL-185) (human lungcarcinoma); G-361 (ATCC No. CRL-1424) (human melanoma); and Caki-1 (ATCCNo. HTB-46) (human renal carcinoma). In addition, IL-22-responsive celllines can be constructed, for example, the Baf3/cytoR11/CRF2-4 cell linedescribed herein (WIPO Publication No. WO 02/12345). These cells can beused in assays to assess the functionality of IL-22RA as an IL-20 orIL-22 antagonist or anti-inflammatory factor.

An additional screening approach provided by the present inventionincludes the use of hybrid receptor polypeptides. These hybridpolypeptides fall into two general classes. Within the first class, theintracellular domain of IL-22RA, is joined to the ligand-binding domainof a second receptor. A second class of hybrid receptor polypeptidescomprise the extracellular (ligand-binding) domain of IL-22RA (SEQ IDNO:3) with an intracellular domain of a second receptor, preferably ahematopoietic cytokine receptor, and a transmembrane domain. HybridIL-22RA monomers, homodimers, heterodimers and multimers of the presentinvention receptors of this second class are expressed in cells known tobe capable of responding to signals transduced by the second receptor.Together, these two classes of hybrid receptors enable theidentification of a responsive cell type for the development of an assayfor detecting IL-22 or IL-20. Moreover, such cells can be used in thepresence of IL-22 or IL-20 to assay the soluble receptor antagonists ofthe present invention in a competition-type assay. In such assay, adecrease in the proliferation or signal transduction activity of IL-22or IL-20 in the presence of a soluble receptor of the present inventiondemonstrates antagonistic activity. Moreover IL-22RA-soluble receptorbinding assays, an cell-based assays, can also be used to assess whethera soluble receptor binds, blocks, inhibits, reduces, antagonizes orneutralizes IL-22 or IL-20 activity.

6. Production of IL-22RA Fusion Proteins and Conjugates

One general class of IL-22RA analogs are variants having an amino acidsequence that is a mutation of the amino acid sequence disclosed herein.Another general class of IL-22RA analogs is provided by anti-idiotypeantibodies, and fragments thereof, as described below. Moreover,recombinant antibodies comprising anti-idiotype variable domains can beused as analogs (see, for example, Monfardini et al., Proc. Assoc. Am.Physicians 108:420 (1996)). Since the variable domains of anti-idiotypeIL-22RA antibodies mimic IL-22RA, these domains can provide IL-22RAbinding activity. Methods of producing anti-idiotypic catalyticantibodies are known to those of skill in the art (see, for example,Joron et al., Ann. N Y Acad. Sci. 672:216 (1992), Friboulet et al.,Appl. Biochem. Biotechnol. 47:229 (1994), and Avalle et al., Ann. N YAcad. Sci. 864:118 (1998)).

Another approach to identifying IL-22RA analogs is provided by the useof combinatorial libraries. Methods for constructing and screening phagedisplay and other combinatorial libraries are provided, for example, byKay et al., Phage Display of Peptides and Proteins (Academic Press1996), Verdine, U.S. Pat. No. 5,783,384, Kay, et. al., U.S. Pat. No.5,747,334, and Kauffman et al., U.S. Pat. No. 5,723,323.

IL-22RA polypeptides have both in vivo and in vitro uses. As anillustration, a soluble form of IL-22RA can be added to cell culturemedium to inhibit the effects of the IL-22RA ligand produced by thecultured cells.

Fusion proteins of IL-22RA can be used to express IL-22RA in arecombinant host, and to isolate the produced IL-22RA. As describedbelow, particular IL-22RA fusion proteins also have uses in diagnosisand therapy. One type of fusion protein comprises a peptide that guidesa IL-22RA polypeptide from a recombinant host cell. To direct a IL-22RApolypeptide into the secretory pathway of a eukaryotic host cell, asecretory signal sequence (also known as a signal peptide, a leadersequence, prepro sequence or pre sequence) is provided in the IL-22RAexpression vector. While the secretory signal sequence may be derivedfrom IL-22RA, a suitable signal sequence may also be derived fromanother secreted protein or synthesized de novo. The secretory signalsequence is operably linked to a IL-22RA-encoding sequence such that thetwo sequences are joined in the correct reading frame and positioned todirect the newly synthesized polypeptide into the secretory pathway ofthe host cell. Secretory signal sequences are commonly positioned 5′ tothe nucleotide sequence encoding the polypeptide of interest, althoughcertain secretory signal sequences may be positioned elsewhere in thenucleotide sequence of interest (see, e.g., Welch et al., U.S. Pat. No.5,037,743; Holland et al., U.S. Pat. No. 5,143,830).

Although the secretory signal sequence of IL-22RA or another proteinproduced by mammalian cells (e.g., tissue-type plasminogen activatorsignal sequence, as described, for example, in U.S. Pat. No. 5,641,655)is useful for expression of IL-22RA in recombinant mammalian hosts, ayeast signal sequence is preferred for expression in yeast cells.Examples of suitable yeast signal sequences are those derived from yeastmating phermone α-factor (encoded by the MFα1 gene), invertase (encodedby the SUC2 gene), or acid phosphatase (encoded by the PHO5 gene). See,for example, Romanos et al., “Expression of Cloned Genes in Yeast,” inDNA Cloning 2: A Practical Approach, 2^(nd) Edition, Glover and Hames(eds.), pages 123-167 (Oxford University Press 1995).

IL-22RA soluble receptor polypeptides can be prepared by expressing atruncated DNA encoding the extracellular domain, for example, apolypeptide which contains SEQ ID NO:3, or the corresponding region of anon-human receptor. It is preferred that the extracellular domainpolypeptides be prepared in a form substantially free of transmembraneand intracellular polypeptide segments. To direct the export of thereceptor domain from the host cell, the receptor DNA is linked to asecond DNA segment encoding a secretory peptide, such as a t-PAsecretory peptide. To facilitate purification of the secreted receptordomain, a C-terminal extension, such as a poly-histidine tag, substanceP, Flag™ peptide (Hopp et al., Biotechnology 6:1204-1210, (1988);available from Eastman Kodak Co., New Haven, Conn.) or anotherpolypeptide or protein for which an antibody or other specific bindingagent is available, can be fused to the receptor polypeptide. Moreover,IL-22RA antigenic epitopes from the extracellular cytokine bindingdomains are also prepared as described above.

In an alternative approach, a receptor extracellular domain of IL-22RAor other class I or II cytokine receptor component can be expressed as afusion with immunoglobulin heavy chain constant regions, typically anF_(c) fragment, which contains two constant region domains and a hingeregion but lacks the variable region (See, Sledziewski, A Z et al., U.S.Pat. Nos. 6,018,026 and 5,750,375). The soluble IL-22RA polypeptides ofthe present invention include such fusions. One such fusion is shown inSEQ ID NO:4. Such fusions are typically secreted as multimeric moleculeswherein the Fc portions are disulfide bonded to each other and tworeceptor polypeptides are arrayed in closed proximity to each other.Fusions of this type can be used to affinity purify the cognate ligandfrom solution, as an in vitro assay tool, to block, inhibit or reducesignals in vitro by specifically titrating out ligand, and asantagonists in vivo by administering them parenterally to bindcirculating ligand and clear it from the circulation. To purify ligand,a IL-22RA-Ig chimera is added to a sample containing the ligand (e.g.,cell-conditioned culture media or tissue extracts) under conditions thatfacilitate receptor-ligand binding (typically near-physiologicaltemperature, pH, and ionic strength). The chimera-ligand complex is thenseparated by the mixture using protein A, which is immobilized on asolid support (e.g., insoluble resin beads). The ligand is then elutedusing conventional chemical techniques, such as with a salt or pHgradient. In the alternative, the chimera itself can be bound to a solidsupport, with binding and elution carried out as above. The chimeras maybe used in vivo to regulate inflammatory responses including acute phaseresponses such as serum amyloid A (SAA), C-reactive protein (CRP), andthe like. Chimeras with high binding affinity are administeredparenterally (e.g., by intramuscular, subcutaneous or intravenousinjection). Circulating molecules bind ligand and are cleared fromcirculation by normal physiological processes. For use in assays, thechimeras are bound to a support via the F_(c) region and used in anELISA format.

To assist in isolating anti-IL-22RA and binding partners of the presentinvention, an assay system that uses a ligand-binding receptor (or anantibody, one member of a complement/anti-complement pair) or a bindingfragment thereof, and a commercially available biosensor instrument(BIAcore, Pharmacia Biosensor, Piscataway, N.J.) may be advantageouslyemployed. Such receptor, antibody, member of acomplement/anti-complement pair or fragment is immobilized onto thesurface of a receptor chip. Use of this instrument is disclosed byKarlsson, J. Immunol. Methods 145:229-40, 1991 and Cunningham and Wells,J. Mol. Biol. 234:554-63, 1993. A receptor, antibody, member or fragmentis covalently attached, using amine or sulfhydryl chemistry, to dextranfibers that are attached to gold film within the flow cell. A testsample is passed through the cell. If a ligand, epitope, or oppositemember of the complement/anti-complement pair is present in the sample,it will bind to the immobilized receptor, antibody or member,respectively, causing a change in the refractive index of the medium,which is detected as a change in surface plasmon resonance of the goldfilm. This system allows the determination of on- and off-rates, fromwhich binding affinity can be calculated, and assessment ofstoichiometry of binding. Alternatively, ligand/receptor binding can beanalyzed using SELDI™ technology (Ciphergen, Inc., Palo Alto, Calif.).Moreover, BIACORE technology, described above, can be used to be used incompetition experiments to determine if different monoclonal antibodiesbind the same or different epitopes on the IL-22RA polypeptide, and assuch, be used to aid in epitope mapping of neutralizing antibodies ofthe present invention that bind, block, inhibit, reduce, antagonize orneutralize IL-22 or both IL-20 and IL-22.

Ligand-binding receptor polypeptides can also be used within other assaysystems known in the art. Such systems include Scatchard analysis fordetermination of binding affinity (see Scatchard, Ann. NY Acad. Sci. 51:660-72, 1949) and calorimetric assays (Cunningham et al., Science253:545-48, 1991; Cunningham et al., Science 245:821-25, 1991).

The present invention further provides a variety of other polypeptidefusions and related multimeric proteins comprising one or morepolypeptide fusions. For example, a soluble IL-22RA receptor can beprepared as a fusion to a dimerizing protein as disclosed in U.S. Pat.Nos. 5,155,027 and 5,567,584. Preferred dimerizing proteins in thisregard include immunoglobulin constant region domains, e.g., IgGγ1, andthe human κ light chain. Immunoglobulin-soluble IL-22RA fusions can beexpressed in genetically engineered cells to produce a variety ofmultimeric IL-22RA receptor analogs. Auxiliary domains can be fused tosoluble IL-22RA receptor to target them to specific cells, tissues, ormacromolecules (e.g., collagen, or cells expressing the IL-22RA ligands,IL-22 or IL-20). A IL-22RA polypeptide can be fused to two or moremoieties, such as an affinity tag for purification and a targetingdomain. Polypeptide fusions can also comprise one or more cleavagesites, particularly between domains. See, Tuan et al., Connective TissueResearch 34: 1-9, 1996.

In bacterial cells, it is often desirable to express a heterologousprotein as a fusion protein to decrease toxicity, increase stability,and to enhance recovery of the expressed protein. For example, IL-22RAcan be expressed as a fusion protein comprising a glutathioneS-transferase polypeptide. Glutathione S-transferease fusion proteinsare typically soluble, and easily purifiable from E. coli lysates onimmobilized glutathione columns. In similar approaches, a IL-22RA fusionprotein comprising a maltose binding protein polypeptide can be isolatedwith an amylose resin column, while a fusion protein comprising theC-terminal end of a truncated Protein A gene can be purified usingIgG-Sepharose. Established techniques for expressing a heterologouspolypeptide as a fusion protein in a bacterial cell are described, forexample, by Williams et al., “Expression of Foreign Proteins in E. coliUsing Plasmid Vectors and Purification of Specific PolyclonalAntibodies,” in DNA Cloning 2: A Practical Approach, 2^(nd) Edition,Glover and Hames (Eds.), pages 15-58 (Oxford University Press 1995). Inaddition, commercially available expression systems are available. Forexample, the PINPOINT Xa protein purification system (PromegaCorporation; Madison, Wis.) provides a method for isolating a fusionprotein comprising a polypeptide that becomes biotinylated duringexpression with a resin that comprises avidin.

Peptide tags that are useful for isolating heterologous polypeptidesexpressed by either prokaryotic or eukaryotic cells includepolyHistidine tags (which have an affinity for nickel-chelating resin),c-myc tags, calmodulin binding protein (isolated with calmodulinaffinity chromatography), substance P, the RYIRS tag (which binds withanti-RYIRS antibodies), the Glu-Glu tag, and the FLAG tag (which bindswith anti-FLAG antibodies). See, for example, Luo et al., Arch. Biochem.Biophys. 329:215 (1996), Morganti et al., Biotechnol. Appl. Biochem.23:67 (1996), and Zheng et al., Gene 186:55 (1997). Nucleic acidmolecules encoding such peptide tags are available, for example, fromSigma-Aldrich Corporation (St. Louis, Mo.).

Another form of fusion protein comprises a IL-22RA polypeptide and animmunoglobulin heavy chain constant region, typically an F_(c) fragment,which contains two or three constant region domains and a hinge regionbut lacks the variable region. As an illustration, Chang et al., U.S.Pat. No. 5,723,125, describe a fusion protein comprising a humaninterferon and a human immunoglobulin Fc fragment. The C-terminal of theinterferon is linked to the N-terminal of the Fc fragment by a peptidelinker moiety. An example of a peptide linker is a peptide comprisingprimarily a T cell inert sequence, which is immunologically inert. Anexemplary peptide linker has the amino acid sequence: GGSGG SGGGG SGGGGS (SEQ ID NO:9). In this fusion protein, an illustrative Fc moiety is ahuman γ4 chain, which is stable in solution and has little or nocomplement activating activity. Accordingly, the present inventioncontemplates a IL-22RA fusion protein that comprises a IL-22RA moietyand a human Fc fragment, wherein the C-terminus of the IL-22RA moiety isattached to the N-terminus of the Fc fragment via a peptide linker, suchas a peptide comprising the amino acid sequence of SEQ ID NO:4. TheIL-22RA moiety can be a IL-22RA molecule or a fragment thereof. Forexample, a fusion protein can comprise the amino acid of SEQ ID NO:3 andan Fc fragment (e.g., a human Fc fragment) (SEQ ID NO:4).

In another variation, a IL-22RA fusion protein comprises an IgGsequence, a IL-22RA moiety covalently joined to the aminoterminal end ofthe IgG sequence, and a signal peptide that is covalently joined to theaminoterminal of the IL-22RA moiety, wherein the IgG sequence consistsof the following elements in the following order: a hinge region, a CH₂domain, and a CH₃ domain. Accordingly, the IgG sequence lacks a CH₁domain. The IL-22RA moiety displays a IL-22RA activity, as describedherein, such as the ability to bind with a IL-22RA ligand. This generalapproach to producing fusion proteins that comprise both antibody andnonantibody portions has been described by LaRochelle et al., EP 742830(WO 95/21258).

Fusion proteins comprising a IL-22RA moiety and an Fc moiety can beused, for example, as an in vitro assay tool. For example, the presenceof a IL-22RA ligand in a biological sample can be detected using aIL-22RA-immunoglobulin fusion protein, in which the IL-22RA moiety isused to bind the ligand, and a macromolecule, such as Protein A oranti-Fc antibody, is used to bind the fusion protein to a solid support.Such systems can be used to identify agonists and antagonists thatinterfere with the binding of a IL-22RA ligands, e.g., IL-22 or bothIL-20 and IL-22, to their receptor.

Other examples of antibody fusion proteins include polypeptides thatcomprise an antigen-binding domain and a IL-22RA fragment that containsa IL-22RA extracellular domain. Such molecules can be used to targetparticular tissues for the benefit of IL-22RA binding activity.

The present invention further provides a variety of other polypeptidefusions. For example, part or all of a domain(s) conferring a biologicalfunction can be swapped between IL-22RA of the present invention withthe functionally equivalent domain(s) from another member of thecytokine receptor family. Polypeptide fusions can be expressed inrecombinant host cells to produce a variety of IL-22RA fusion analogs. AIL-22RA polypeptide can be fused to two or more moieties or domains,such as an affinity tag for purification and a targeting domain.Polypeptide fusions can also comprise one or more cleavage sites,particularly between domains. See, for example, Tuan et al., ConnectiveTissue Research 34:1 (1996).

Fusion proteins can be prepared by methods known to those skilled in theart by preparing each component of the fusion protein and chemicallyconjugating them. Alternatively, a polynucleotide encoding bothcomponents of the fusion protein in the proper reading frame can begenerated using known techniques and expressed by the methods describedherein. General methods for enzymatic and chemical cleavage of fusionproteins are described, for example, by Ausubel (1995) at pages 16-19 to16-25.

IL-22RA binding domains can be further characterized by physicalanalysis of structure, as determined by such techniques as nuclearmagnetic resonance, crystallography, electron diffraction orphotoaffinity labeling, in conjunction with mutation of putative contactsite amino acids of IL-22RA ligand agonists. See, for example, de Vos etal., Science 255:306 (1992), Smith et al., J. Mol. Biol. 224:899 (1992),and Wlodaver et al., FEBS Lett. 309:59 (1992).

The present invention also contemplates chemically modified IL-22RAcompositions, in which a IL-22RA polypeptide is linked with a polymer.Illustrative IL-22RA polypeptides are soluble polypeptides that lack afunctional transmembrane domain, such as a polypeptide consisting ofamino acid residues SEQ ID NO:3. Typically, the polymer is water solubleso that the IL-22RA conjugate does not precipitate in an aqueousenvironment, such as a physiological environment. An example of asuitable polymer is one that has been modified to have a single reactivegroup, such as an active ester for acylation, or an aldehyde foralkylation. In this way, the degree of polymerization can be controlled.An example of a reactive aldehyde is polyethylene glycolpropionaldehyde, or mono-(C1-C10) alkoxy, or aryloxy derivatives thereof(see, for example, Harris, et al., U.S. Pat. No. 5,252,714). The polymermay be branched or unbranched. Moreover, a mixture of polymers can beused to produce IL-22RA conjugates.

IL-22RA conjugates used for therapy can comprise pharmaceuticallyacceptable water-soluble polymer moieties. Suitable water-solublepolymers include polyethylene glycol (PEG), monomethoxy-PEG,mono-(C1-C10)alkoxy-PEG, aryloxy-PEG, poly-(N-vinyl pyrrolidone)PEG,tresyl monomethoxy PEG, PEG propionaldehyde, bis-succinimidyl carbonatePEG, propylene glycol homopolymers, a polypropylene oxide/ethylene oxideco-polymer, polyoxyethylated polyols (e.g., glycerol), polyvinylalcohol, dextran, cellulose, or other carbohydrate-based polymers.Suitable PEG may have a molecular weight from about 600 to about 60,000,including, for example, 5,000, 12,000, 20,000 and 25,000. A IL-22RAconjugate can also comprise a mixture of such water-soluble polymers.

One example of a IL-22RA conjugate comprises a IL-22RA moiety and apolyalkyl oxide moiety attached to the N-terminus of the IL-22RA moiety.PEG is one suitable polyalkyl oxide. As an illustration, IL-22RA can bemodified with PEG, a process known as “PEGylation.” PEGylation ofIL-22RA can be carried out by any of the PEGylation reactions known inthe art (see, for example, EP 0 154 316, Delgado et al., CriticalReviews in Therapeutic Drug Carrier Systems 9:249 (1992), Duncan andSpreafico, Clin. Pharmacokinet. 27:290 (1994), and Francis et al., Int JHematol 68:1 (1998)). For example, PEGylation can be performed by anacylation reaction or by an alkylation reaction with a reactivepolyethylene glycol molecule. In an alternative approach, IL-22RAconjugates are formed by condensing activated PEG, in which a terminalhydroxy or amino group of PEG has been replaced by an activated linker(see, for example, Karasiewicz et al., U.S. Pat. No. 5,382,657).

PEGylation by acylation typically requires reacting an active esterderivative of PEG with a IL-22RA polypeptide. An example of an activatedPEG ester is PEG esterified to N-hydroxysuccinimide. As used herein, theterm “acylation” includes the following types of linkages betweenIL-22RA and a water soluble polymer: amide, carbamate, urethane, and thelike. Methods for preparing PEGylated IL-22RA by acylation willtypically comprise the steps of (a) reacting a IL-22RA polypeptide withPEG (such as a reactive ester of an aldehyde derivative of PEG) underconditions whereby one or more PEG groups attach to IL-22RA, and (b)obtaining the reaction product(s). Generally, the optimal reactionconditions for acylation reactions will be determined based upon knownparameters and desired results. For example, the larger the ratio ofPEG:IL-22RA, the greater the percentage of polyPEGylated IL-22RAproduct.

The product of PEGylation by acylation is typically a polyPEGylatedIL-22RA product, wherein the lysine ε-amino groups are PEGylated via anacyl linking group. An example of a connecting linkage is an amide.Typically, the resulting IL-22RA will be at least 95% mono-, di-, ortri-pegylated, although some species with higher degrees of PEGylationmay be formed depending upon the reaction conditions. PEGylated speciescan be separated from unconjugated IL-22RA polypeptides using standardpurification methods, such as dialysis, ultrafiltration, ion exchangechromatography, affinity chromatography, and the like.

PEGylation by alkylation generally involves reacting a terminal aldehydederivative of PEG with IL-22RA in the presence of a reducing agent. PEGgroups can be attached to the polypeptide via a —CH₂—NH group.

Moreover, anti-IL-22RA antibodies or antibody fragments of the presentinvention can be PEGylated using methods in the art and describedherein.

Derivatization via reductive alkylation to produce a monoPEGylatedproduct takes advantage of the differential reactivity of differenttypes of primary amino groups available for derivatization. Typically,the reaction is performed at a pH that allows one to take advantage ofthe pKa differences between the ε-amino groups of the lysine residuesand the α-amino group of the N-terminal residue of the protein. By suchselective derivatization, attachment of a water-soluble polymer thatcontains a reactive group such as an aldehyde, to a protein iscontrolled. The conjugation with the polymer occurs predominantly at theN-terminus of the protein without significant modification of otherreactive groups such as the lysine side chain amino groups. The presentinvention provides a substantially homogenous preparation of IL-22RAmonopolymer conjugates.

Reductive alkylation to produce a substantially homogenous population ofmonopolymer IL-22RA conjugate molecule can comprise the steps of: (a)reacting a IL-22RA polypeptide with a reactive PEG under reductivealkylation conditions at a pH suitable to permit selective modificationof the α-amino group at the amino terminus of the IL-22RA, and (b)obtaining the reaction product(s). The reducing agent used for reductivealkylation should be stable in aqueous solution and able to reduce onlythe Schiff base formed in the initial process of reductive alkylation.Illustrative reducing agents include sodium borohydride, sodiumcyanoborohydride, dimethylamine borane, trimethylamine borane, andpyridine borane.

For a substantially homogenous population of monopolymer IL-22RAconjugates, the reductive alkylation reaction conditions are those thatpermit the selective attachment of the water-soluble polymer moiety tothe N-terminus of IL-22RA. Such reaction conditions generally providefor pKa differences between the lysine amino groups and the α-aminogroup at the N-terminus. The pH also affects the ratio of polymer toprotein to be used. In general, if the pH is lower, a larger excess ofpolymer to protein will be desired because the less reactive theN-terminal α-group, the more polymer is needed to achieve optimalconditions. If the pH is higher, the polymer:IL-22RA need not be aslarge because more reactive groups are available. Typically, the pH willfall within the range of 3 to 9, or 3 to 6. This method can be employedfor making IL-22RA-comprising homodimeric, heterodimeric or multimericsoluble receptor conjugates.

Another factor to consider is the molecular weight of the water-solublepolymer. Generally, the higher the molecular weight of the polymer, thefewer number of polymer molecules which may be attached to the protein.For PEGylation reactions, the typical molecular weight is about 2 kDa toabout 100 kDa, about 5 kDa to about 50 kDa, or about 12 kDa to about 25kDa. The molar ratio of water-soluble polymer to IL-22RA will generallybe in the range of 1:1 to 100:1. Typically, the molar ratio ofwater-soluble polymer to IL-22RA will be 1:1 to 20:1 for polyPEGylation,and 1:1 to 5:1 for monoPEGylation.

General methods for producing conjugates comprising a polypeptide andwater-soluble polymer moieties are known in the art. See, for example,Karasiewicz et al., U.S. Pat. No. 5,382,657, Greenwald et al., U.S. Pat.No. 5,738,846, Nieforth et al., Clin. Pharmacol. Ther. 59:636 (1996),Monkarsh et al., Anal. Biochem. 247:434 (1997)). This method can beemployed for making IL-22RA-comprising homodimeric, heterodimeric ormultimeric soluble receptor conjugates.

The present invention contemplates compositions comprising a peptide orpolypeptide, such as a soluble receptor or antibody described herein.Such compositions can further comprise a carrier. The carrier can be aconventional organic or inorganic carrier. Examples of carriers includewater, buffer solution, alcohol, propylene glycol, macrogol, sesame oil,corn oil, and the like.

7. Isolation of IL-22RA Polypeptides

The polypeptides of the present invention can be purified to at leastabout 80% purity, to at least about 90% purity, to at least about 95%purity, or greater than 95%, such as 96%, 97%, 98%, or greater than 99%purity with respect to contaminating macromolecules, particularly otherproteins and nucleic acids, and free of infectious and pyrogenic agents.The polypeptides of the present invention may also be purified to apharmaceutically pure state, which is greater than 99.9% pure. Incertain preparations, purified polypeptide is substantially free ofother polypeptides, particularly other polypeptides of animal origin.

Fractionation and/or conventional purification methods can be used toobtain preparations of IL-22RA purified from natural sources (e.g.,human tissue sources), synthetic IL-22RA polypeptides, and recombinantIL-22RA polypeptides and fusion IL-22RA polypeptides purified fromrecombinant host cells. In general, ammonium sulfate precipitation andacid or chaotrope extraction may be used for fractionation of samples.Exemplary purification steps may include hydroxyapatite, size exclusion,FPLC and reverse-phase high performance liquid chromatography. Suitablechromatographic media include derivatized dextrans, agarose, cellulose,polyacrylamide, specialty silicas, and the like. PEI, DEAE, QAE and Qderivatives are suitable. Exemplary chromatographic media include thosemedia derivatized with phenyl, butyl, or octyl groups, such asPhenyl-Sepharose FF (Pharmacia), Toyopearl butyl 650 (Toso Haas,Montgomeryville, Pa.), Octyl-Sepharose (Pharmacia) and the like; orpolyacrylic resins, such as Amberchrom CG 71 (Toso Haas) and the like.Suitable solid supports include glass beads, silica-based resins,cellulosic resins, agarose beads, cross-linked agarose beads,polystyrene beads, cross-linked polyacrylamide resins and the like thatare insoluble under the conditions in which they are to be used. Thesesupports may be modified with reactive groups that allow attachment ofproteins by amino groups, carboxyl groups, sulfhydryl groups, hydroxylgroups and/or carbohydrate moieties.

Examples of coupling chemistries include cyanogen bromide activation,N-hydroxysuccinimide activation, epoxide activation, sulfhydrylactivation, hydrazide activation, and carboxyl and amino derivatives forcarbodiimide coupling chemistries. These and other solid media are wellknown and widely used in the art, and are available from commercialsuppliers. Selection of a particular method for polypeptide isolationand purification is a matter of routine design and is determined in partby the properties of the chosen support. See, for example, AffinityChromatography: Principles & Methods (Pharmacia LKB Biotechnology 1988),and Doonan, Protein Purification Protocols (The Humana Press 1996).

Additional variations in IL-22RA isolation and purification can bedevised by those of skill in the art. For example, anti-IL-22RAantibodies, obtained as described below, can be used to isolate largequantities of protein by immunoaffinity purification.

The polypeptides of the present invention can also be isolated byexploitation of particular properties. For example, immobilized metalion adsorption (IMAC) chromatography can be used to purifyhistidine-rich proteins, including those comprising polyhistidine tags.Briefly, a gel is first charged with divalent metal ions to form achelate (Sulkowski, Trends in Biochem. 3:1 (1985)). Histidine-richproteins will be adsorbed to this matrix with differing affinities,depending upon the metal ion used, and will be eluted by competitiveelution, lowering the pH, or use of strong chelating agents. Othermethods of purification include purification of glycosylated proteins bylectin affinity chromatography and ion exchange chromatography (M.Deutscher, (ed.), Meth. Enzymol. 182:529 (1990)). Within additionalembodiments of the invention, a fusion of the polypeptide of interestand an affinity tag (e.g., maltose-binding protein, an immunoglobulindomain) may be constructed to facilitate purification. Moreover, theligand-binding properties of IL-22RA extracellular domain can beexploited for purification, for example, of IL-22RA-comprising solublereceptors; for example, by using affinity chromatography wherein IL-22ligand is bound to a column and the IL-22RA-comprising receptor is boundand subsequently eluted using standard chromatography methods.

IL-22RA polypeptides or fragments thereof may also be prepared throughchemical synthesis, as described above. IL-22RA polypeptides may bemonomers or multimers; glycosylated or non-glycosylated; PEGylated ornon-PEGylated; and may or may not include an initial methionine aminoacid residue.

8. Production of Antibodies to IL-22RA Proteins

Antibodies to IL-22RA can be obtained, for example, using the product ofa IL-22RA expression vector or IL-22RA isolated from a natural source asan antigen. Particularly useful anti-IL-22RA antibodies “bindspecifically” with IL-22RA. Antibodies are considered to be specificallybinding if the antibodies exhibit at least one of the following twoproperties: (1) antibodies bind to IL-22RA with a threshold level ofbinding activity, and (2) antibodies do not significantly cross-reactwith polypeptides related to IL-22RA.

With regard to the first characteristic, antibodies specifically bind ifthey bind to a IL-22RA polypeptide, peptide or epitope with a bindingaffinity (K_(a)) of 10⁶ M⁻¹ or greater, preferably 10⁷ M⁻¹ or greater,more preferably 10⁸ M⁻¹ or greater, and most preferably 10⁹ M⁻¹ orgreater. The binding affinity of an antibody can be readily determinedby one of ordinary skill in the art, for example, by Scatchard analysis(Scatchard, Ann. NY Acad. Sci. 51:660 (1949)). With regard to the secondcharacteristic, antibodies do not significantly cross-react with relatedpolypeptide molecules, for example, if they detect IL-22RA, but notpresently known polypeptides using a standard Western blot analysis.Examples of known related polypeptides include known cytokine receptors.

Anti-IL-22RA antibodies can be produced using antigenic IL-22RAepitope-bearing peptides and polypeptides. Antigenic epitope-bearingpeptides and polypeptides of the present invention contain a sequence ofat least nine, or between 15 to about 30 amino acids contained withinSEQ ID NO:3 or another amino acid sequence disclosed herein. However,peptides or polypeptides comprising a larger portion of an amino acidsequence of the invention, containing from 30 to 50 amino acids, or anylength up to and including the entire amino acid sequence of apolypeptide of the invention, also are useful for inducing antibodiesthat bind with IL-22RA. It is desirable that the amino acid sequence ofthe epitope-bearing peptide is selected to provide substantialsolubility in aqueous solvents (i.e., the sequence includes relativelyhydrophilic residues, while hydrophobic residues are typically avoided).Moreover, amino acid sequences containing proline residues may be alsobe desirable for antibody production.

As an illustration, potential antigenic sites in IL-22RA were identifiedusing the Jameson-Wolf method, Jameson and Wolf, CABIOS 4:181, (1988),as implemented by the PROTEAN program (version 3.14) of LASERGENE(DNASTAR; Madison, Wis.). Default parameters were used in this analysis.

The Jameson-Wolf method predicts potential antigenic determinants bycombining six major subroutines for protein structural prediction.Briefly, the Hopp-Woods method, Hopp et al., Proc. Nat'l Acad. Sci. USA78:3824 (1981), was first used to identify amino acid sequencesrepresenting areas of greatest local hydrophilicity (parameter: sevenresidues averaged). In the second step, Emini's method, Emini et al., J.Virology 55:836 (1985), was used to calculate surface probabilities(parameter: surface decision threshold (0.6)=1). Third, theKarplus-Schultz method, Karplus and Schultz, Naturwissenschaften 72:212(1985), was used to predict backbone chain flexibility (parameter:flexibility threshold (0.2)=1). In the fourth and fifth steps of theanalysis, secondary structure predictions were applied to the data usingthe methods of Chou-Fasman, Chou, “Prediction of Protein StructuralClasses from Amino Acid Composition,” in Prediction of Protein Structureand the Principles of Protein Conformation, Fasman (ed.), pages 549-586(Plenum Press 1990), and Garnier-Robson, Garnier et al., J. Mol. Biol.120:97 (1978) (Chou-Fasman parameters: conformation table=64 proteins; αregion threshold=103; β region threshold=105; Garnier-Robson parameters:α and β decision constants=0). In the sixth subroutine, flexibilityparameters and hydropathy/solvent accessibility factors were combined todetermine a surface contour value, designated as the “antigenic index.”Finally, a peak broadening function was applied to the antigenic index,which broadens major surface peaks by adding 20, 40, 60, or 80% of therespective peak value to account for additional free energy derived fromthe mobility of surface regions relative to interior regions. Thiscalculation was not applied, however, to any major peak that resides ina helical region, since helical regions tend to be less flexible.

The results of this analysis indicated that the following amino acidsequences of SEQ ID NO:3 would provide suitable antigenic peptides:Hopp/Woods hydrophilicity profiles can be used to determine regions thathave the most antigenic potential within SEQ ID NO:3 (Hopp et al., Proc.Natl. Acad. Sci. 78:3824-3828, 1981; Hopp, J. Immun. Meth. 88:1-18, 1986and Triquier et al., Protein Engineering 11:153-169, 1998). The profileis based on a sliding six-residue window. Buried G, S, and T residuesand exposed H, Y, and W residues were ignored. Moreover, IL-22RAantigenic epitopes within SEQ ID NO:3 as predicted by a Jameson-Wolfplot, e.g., using DNASTAR Protean program (DNASTAR, Inc., Madison, Wis.)serve as preferred antigenic epitopes, and can be determined by one ofskill in the art. Such antigenic epitopes include (1) amino acidresidues 1 (Pro) to 6 (Asp) of SEQ ID NO:3; (2) amino acid residues 26(Ser) to 32 (Pro) of SEQ ID NO:3; (3) amino acid residues 41 (Lys) to 47(Asp) of SEQ ID NO:3; (4) amino acid residues 49 (Val) to 62 (Cys) ofSEQ ID NO:3; (5) amino acid residues 41 (Lys) to 62 (Cys) of SEQ IDNO:3; (6) amino acid residues 84 (Ala) to 97 (Ser) of SEQ ID NO:3; (7)amino acid residues 103 (Thr) to 108 (Asp) of SEQ ID NO:3; (8) aminoacid residues 130 (Arg) to 135 (His) of SEQ ID NO:3; (9) amino acidresidues 164 (Gly) to 166 (Lys) of SEQ ID NO:3; (10) amino acid residues175 (Tyr) to 179 (Glu) of SEQ ID NO:3; (11) amino acid residues 193(Lys) to 196 (Ala) of SEQ ID NO:3; (12) amino acid residues 203 (Lys) to209 (Thr) of SEQ ID NO:3. The present invention contemplates the use ofany one of antigenic peptides 1 to 12 to generate antibodies to IL-22RAor as a tool to screen or identify neutralizing monoclonal antibodies ofthe present invention. The present invention also contemplatespolypeptides comprising at least one of antigenic peptides 1 to 10. Thepresent invention contemplates the use of any antigenic peptides orepitopes described herein to generate antibodies to IL-22RA, as well asto identify and screen anti-IL-22RA monoclonal antibodies that areneutralizing, and that may bind, block, inhibit, reduce, antagonize orneutralize the activity of IL-22 and IL-20 (individually or together).

Moreover, suitable antigens also include the IL-22RA polypeptidescomprising a IL-22RA cytokine binding, or extracellular domain disclosedabove in combination with another class I or II cytokine extracellulardomain, such as those that form soluble IL-22RA heterodimeric ormultimeric polypeptides, such as soluble IL-22RA/CRF2-4,IL-22RA/zcytor11, IL-22RA/zcytor7, and the like.

Polyclonal antibodies to recombinant IL-22RA protein or to IL-22RAisolated from natural sources can be prepared using methods well-knownto those of skill in the art. See, for example, Green et al.,“Production of Polyclonal Antisera,” in Immunochemical Protocols(Manson, ed.), pages 1-5 (Humana Press 1992), and Williams et al.,“Expression of foreign proteins in E. coli using plasmid vectors andpurification of specific polyclonal antibodies,” in DNA Cloning 2:Expression Systems, 2nd Edition, Glover et al. (eds.), page 15 (OxfordUniversity Press 1995). The immunogenicity of a IL-22RA polypeptide canbe increased through the use of an adjuvant, such as alum (aluminumhydroxide) or Freund's complete or incomplete adjuvant. Polypeptidesuseful for immunization also include fusion polypeptides, such asfusions of IL-22RA or a portion thereof with an immunoglobulinpolypeptide or with maltose binding protein. The polypeptide immunogenmay be a full-length molecule or a portion thereof. If the polypeptideportion is “hapten-like,” such portion may be advantageously joined orlinked to a macromolecular carrier (such as keyhole limpet hemocyanin(KLH), bovine serum albumin (BSA) or tetanus toxoid) for immunization.

Although polyclonal antibodies are typically raised in animals such ashorses, cows, dogs, chicken, rats, mice, rabbits, guinea pigs, goats, orsheep, an anti-IL-22RA antibody of the present invention may also bederived from a subhuman primate antibody. General techniques for raisingdiagnostically and therapeutically useful antibodies in baboons may befound, for example, in Goldenberg et al., international patentpublication No. WO 91/11465, and in Losman et al., Int. J. Cancer 46:310(1990).

Alternatively, monoclonal anti-IL-22RA antibodies can be generated.Rodent mono-clonal antibodies to specific antigens may be obtained bymethods known to those skilled in the art (see, for example, Kohler etal., Nature 256:495 (1975), Coligan et al. (eds.), Current Protocols inImmunology, Vol. 1, pages 2.5.1-2.6.7 (John Wiley & Sons 1991)[“Coligan”], Picksley et al., “Production of monoclonal antibodiesagainst proteins expressed in E. coli,” in DNA Cloning 2: ExpressionSystems, 2nd Edition, Glover et al. (eds.), page 93 (Oxford UniversityPress 1995)).

Briefly, monoclonal antibodies can be obtained by injecting mice with acomposition comprising a IL-22RA gene product, verifying the presence ofantibody production by removing a serum sample, removing the spleen toobtain B-lymphocytes, fusing the B-lymphocytes with myeloma cells toproduce hybridomas, cloning the hybridomas, selecting positive cloneswhich produce antibodies to the antigen, culturing the clones thatproduce antibodies to the antigen, and isolating the antibodies from thehybridoma cultures.

In addition, an anti-IL-22RA antibody of the present invention may bederived from a human monoclonal antibody. Human monoclonal antibodiesare obtained from transgenic mice that have been engineered to producespecific human antibodies in response to antigenic challenge. In thistechnique, elements of the human heavy and light chain locus areintroduced into strains of mice derived from embryonic stem cell linesthat contain targeted disruptions of the endogenous heavy chain andlight chain loci. The transgenic mice can synthesize human antibodiesspecific for human antigens, and the mice can be used to produce humanantibody-secreting hybridomas. Methods for obtaining human antibodiesfrom transgenic mice are described, for example, by Green et al., NatureGenet. 7:13 (1994), Lonberg et al., Nature 368:856 (1994), and Taylor etal., Int. Immun. 6:579 (1994).

Monoclonal antibodies can be isolated and purified from hybridomacultures by a variety of well-established techniques. Such isolationtechniques include affinity chromatography with Protein-A Sepharose,size-exclusion chromatography, and ion-exchange chromatography (see, forexample, Coligan at pages 2.7.1-2.7.12 and pages 2.9.1-2.9.3; Baines etal., “Purification of Immunoglobulin G (IgG),” in Methods in MolecularBiology, Vol. 10, pages 79-104 (The Humana Press, Inc. 1992)).

For particular uses, it may be desirable to prepare fragments ofanti-IL-22RA antibodies. Such antibody fragments can be obtained, forexample, by proteolytic hydrolysis of the antibody. Antibody fragmentscan be obtained by pepsin or papain digestion of whole antibodies byconventional methods. As an illustration, antibody fragments can beproduced by enzymatic cleavage of antibodies with pepsin to provide a 5Sfragment denoted F(ab′)₂. This fragment can be further cleaved using athiol reducing agent to produce 3.5S Fab′ monovalent fragments.Optionally, the cleavage reaction can be performed using a blockinggroup for the sulfhydryl groups that result from cleavage of disulfidelinkages. As an alternative, an enzymatic cleavage using pepsin producestwo monovalent Fab fragments and an Fc fragment directly. These methodsare described, for example, by Goldenberg, U.S. Pat. No. 4,331,647,Nisonoff et al., Arch Biochem. Biophys. 89:230 (1960), Porter, Biochem.J. 73:119 (1959), Edelman et al., in Methods in Enzymology Vol. 1, page422 (Academic Press 1967), and by Coligan at pages 2.8.1-2.8.10 and2.10.-2.10.4.

Other methods of cleaving antibodies, such as separation of heavy chainsto form monovalent light-heavy chain fragments, further cleavage offragments, or other enzymatic, chemical or genetic techniques may alsobe used, so long as the fragments bind to the antigen that is recognizedby the intact antibody.

For example, Fv fragments comprise an association of V_(H) and V_(L)chains. This association can be noncovalent, as described by Inbar etal., Proc. Nat'l Acad. Sci. USA 69:2659 (1972). Alternatively, thevariable chains can be linked by an intermolecular disulfide bond orcross-linked by chemicals such as glutaraldehyde (see, for example,Sandhu, Crit. Rev. Biotech. 12:437 (1992)).

The Fv fragments may comprise V_(H) and V_(L) chains which are connectedby a peptide linker. These single-chain antigen binding proteins (scFv)are prepared by constructing a structural gene comprising DNA sequencesencoding the V_(H) and V_(L) domains which are connected by anoligonucleotide. The structural gene is inserted into an expressionvector which is subsequently introduced into a host cell, such as E.coli. The recombinant host cells synthesize a single polypeptide chainwith a linker peptide bridging the two V domains. Methods for producingscFvs are described, for example, by Whitlow et al., Methods: ACompanion to Methods in Enzymology 2:97 (1991) (also see, Bird et al.,Science 242:423 (1988), Ladner et al., U.S. Pat. No. 4,946,778, Pack etal., Bio/Technology 11:1271 (1993), and Sandhu, supra).

As an illustration, a scFV can be obtained by exposing lymphocytes toIL-22RA polypeptide in vitro, and selecting antibody display librariesin phage or similar vectors (for instance, through use of immobilized orlabeled IL-22RA protein or peptide). Genes encoding polypeptides havingpotential IL-22RA polypeptide binding domains can be obtained byscreening random peptide libraries displayed on phage (phage display) oron bacteria, such as E. coli. Nucleotide sequences encoding thepolypeptides can be obtained in a number of ways, such as through randommutagenesis and random polynucleotide synthesis. These random peptidedisplay libraries can be used to screen for peptides which interact witha known target which can be a protein or polypeptide, such as a ligandor receptor, a biological or synthetic macromolecule, or organic orinorganic substances. Techniques for creating and screening such randompeptide display libraries are known in the art (Ladner et al., U.S. Pat.No. 5,223,409, Ladner et al., U.S. Pat. No. 4,946,778, Ladner et al.,U.S. Pat. No. 5,403,484, Ladner et al., U.S. Pat. No. 5,571,698, and Kayet al., Phage Display of Peptides and Proteins (Academic Press, Inc.1996)) and random peptide display libraries and kits for screening suchlibraries are available commercially, for instance from CLONTECHLaboratories, Inc. (Palo Alto, Calif.), Invitrogen Inc. (San Diego,Calif.), New England Biolabs, Inc. (Beverly, Mass.), and Pharmacia LKBBiotechnology Inc. (Piscataway, N.J.). Random peptide display librariescan be screened using the IL-22RA sequences disclosed herein to identifyproteins which bind to IL-22RA.

Another form of an antibody fragment is a peptide coding for a singlecomplementarity-determining region (CDR). CDR peptides (“minimalrecognition units”) can be obtained by constructing genes encoding theCDR of an antibody of interest. Such genes are prepared, for example, byusing the polymerase chain reaction to synthesize the variable regionfrom RNA of antibody-producing cells (see, for example, Larrick et al.,Methods: A Companion to Methods in Enzymology 2:106 (1991),Courtenay-Luck, “Genetic Manipulation of Monoclonal Antibodies,” inMonoclonal Antibodies: Production, Engineering and Clinical Application,Ritter et al. (eds.), page 166 (Cambridge University Press 1995), andWard et al., “Genetic Manipulation and Expression of Antibodies,” inMonoclonal Antibodies: Principles and Applications, Birch et al.,(eds.), page 137 (Wiley-Liss, Inc. 1995)).

Alternatively, an anti-IL-22RA antibody may be derived from a“humanized” monoclonal antibody. Humanized monoclonal antibodies areproduced by transferring mouse complementary determining regions fromheavy and light variable chains of the mouse immunoglobulin into a humanvariable domain. Typical residues of human antibodies are thensubstituted in the framework regions of the murine counterparts. The useof antibody components derived from humanized monoclonal antibodiesobviates potential problems associated with the immunogenicity of murineconstant regions. General techniques for cloning murine immunoglobulinvariable domains are described, for example, by Orlandi et al., Proc.Nat'l Acad. Sci. USA 86:3833 (1989). Techniques for producing humanizedmonoclonal antibodies are described, for example, by Jones et al.,Nature 321:522 (1986), Carter et al., Proc. Nat'l Acad. Sci. USA 89:4285(1992), Sandhu, Crit. Rev. Biotech. 12:437 (1992), Singer et al., J.Immun. 150:2844 (1993), Sudhir (ed.), Antibody Engineering Protocols(Humana Press, Inc. 1995), Kelley, “Engineering Therapeutic Antibodies,”in Protein Engineering Principles and Practice, Cleland et al. (eds.),pages 399-434 (John Wiley & Sons, Inc. 1996), and by Queen et al., U.S.Pat. No. 5,693,762 (1997).

Moreover, anti-IL-22RA antibodies or antibody fragments of the presentinvention can be PEGylated using methods in the art and describedherein.

Polyclonal anti-idiotype antibodies can be prepared by immunizinganimals with anti-IL-22RA antibodies or antibody fragments, usingstandard techniques. See, for example, Green et al., “Production ofPolyclonal Antisera,” in Methods In Molecular Biology: ImmunochemicalProtocols, Manson (ed.), pages 1-12 (Humana Press 1992). Also, seeColigan at pages 2.4.1-2.4.7. Alternatively, monoclonal anti-idiotypeantibodies can be prepared using anti-IL-22RA antibodies or antibodyfragments as immunogens with the techniques, described above. As anotheralternative, humanized anti-idiotype antibodies or subhuman primateanti-idiotype antibodies can be prepared using the above-describedtechniques. Methods for producing anti-idiotype antibodies aredescribed, for example, by Irie, U.S. Pat. No. 5,208,146, Greene, et.al., U.S. Pat. No. 5,637,677, and Varthakavi and Minocha, J. Gen. Virol.77:1875 (1996).

An anti-IL-22RA antibody can be conjugated with a detectable label toform an anti-IL-22RA immunoconjugate. Suitable detectable labelsinclude, for example, a radioisotope, a fluorescent label, achemiluminescent label, an enzyme label, a bioluminescent label orcolloidal gold. Methods of making and detecting such detectably-labeledimmunoconjugates are well-known to those of ordinary skill in the art,and are described in more detail below.

The detectable label can be a radioisotope that is detected byautoradiography. Isotopes that are particularly useful for the purposeof the present invention are ³H, ¹²⁵I, ¹³¹I, ³⁵S and ¹⁴C.

Anti-IL-22RA immunoconjugates can also be labeled with a fluorescentcompound. The presence of a fluorescently-labeled antibody is determinedby exposing the immunoconjugate to light of the proper wavelength anddetecting the resultant fluorescence. Fluorescent labeling compoundsinclude fluorescein isothiocyanate, rhodamine, phycoerytherin,phycocyanin, allophycocyanin, o-phthaldehyde and fluorescamine.

Alternatively, anti-IL-22RA immunoconjugates can be detectably labeledby coupling an antibody component to a chemiluminescent compound. Thepresence of the chemiluminescent-tagged immunoconjugate is determined bydetecting the presence of luminescence that arises during the course ofa chemical reaction. Examples of chemiluminescent labeling compoundsinclude luminol, isoluminol, an aromatic acridinium ester, an imidazole,an acridinium salt and an oxalate ester.

Similarly, a bioluminescent compound can be used to label anti-IL-22RAimmunoconjugates of the present invention. Bioluminescence is a type ofchemiluminescence found in biological systems in which a catalyticprotein increases the efficiency of the chemiluminescent reaction. Thepresence of a bioluminescent protein is determined by detecting thepresence of luminescence. Bioluminescent compounds that are useful forlabeling include luciferin, luciferase and aequorin.

Alternatively, anti-IL-22RA immunoconjugates can be detectably labeledby linking an anti-IL-22RA antibody component to an enzyme. When theanti-IL-22RA-enzyme conjugate is incubated in the presence of theappropriate substrate, the enzyme moiety reacts with the substrate toproduce a chemical moiety which can be detected, for example, byspectrophotometric, fluorometric or visual means. Examples of enzymesthat can be used to detectably label polyspecific immunoconjugatesinclude β-galactosidase, glucose oxidase, peroxidase and alkalinephosphatase.

Those of skill in the art will know of other suitable labels which canbe employed in accordance with the present invention. The binding ofmarker moieties to anti-IL-22RA antibodies can be accomplished usingstandard techniques known to the art. Typical methodology in this regardis described by Kennedy et al., Clin. Chim. Acta 70:1 (1976), Schurs etal., Clin. Chim. Acta 81:1 (1977), Shih et al., Int'l J. Cancer 46:1101(1990), Stein et al., Cancer Res. 50:1330 (1990), and Coligan, supra.

Moreover, the convenience and versatility of immunochemical detectioncan be enhanced by using anti-IL-22RA antibodies that have beenconjugated with avidin, streptavidin, and biotin (see, for example,Wilchek et al. (eds.), “Avidin-Biotin Technology,” Methods InEnzymology, Vol. 184 (Academic Press 1990), and Bayer et al.,“Immunochemical Applications of Avidin-Biotin Technology,” in Methods InMolecular Biology, Vol. 10, Manson (ed.), pages 149-162 (The HumanaPress, Inc. 1992).

Methods for performing immunoassays are well-established. See, forexample, Cook and Self, “Monoclonal Antibodies in DiagnosticImmunoassays,” in Monoclonal Antibodies: Production, Engineering, andClinical Application, Ritter and Ladyman (eds.), pages 180-208,(Cambridge University Press, 1995), Perry, “The Role of MonoclonalAntibodies in the Advancement of Immunoassay Technology,” in MonoclonalAntibodies: Principles and Applications, Birch and Lennox (eds.), pages107-120 (Wiley-Liss, Inc. 1995), and Diamandis, Immunoassay (AcademicPress, Inc. 1996).

The present invention also contemplates kits for performing animmunological diagnostic assay for IL-22RA gene expression. Such kitscomprise at least one container comprising an anti-IL-22RA antibody, orantibody fragment. A kit may also comprise a second container comprisingone or more reagents capable of indicating the presence of IL-22RAantibody or antibody fragments. Examples of such indicator reagentsinclude detectable labels such as a radioactive label, a fluorescentlabel, a chemiluminescent label, an enzyme label, a bioluminescentlabel, colloidal gold, and the like. A kit may also comprise a means forconveying to the user that IL-22RA antibodies or antibody fragments areused to detect IL-22RA protein. For example, writ en instructions maystate that the enclosed antibody or antibody fragment can be used todetect IL-22RA. The written material can be applied directly to acontainer, or the written material can be provided in the form of apackaging insert.

9. Use of Anti-IL-22RA Antibodies to Antagonize IL-22RA Binding to IL-22or both IL-20 and IL-22

Alternative techniques for generating or selecting antibodies usefulherein include in vitro exposure of lymphocytes to soluble IL-22RAreceptor polypeptides or fragments thereof, such as antigenic epitopes,and selection of antibody display libraries in phage or similar vectors(for instance, through use of immobilized or labeled soluble IL-22RAreceptor polypeptides or fragments thereof, such as antigenic epitopes).Genes encoding polypeptides having potential binding domains such assoluble soluble IL-22RA receptor polypeptides or fragments thereof, suchas antigenic epitopes can be obtained by screening random peptidelibraries displayed on phage (phage display) or on bacteria, such as E.coli. Nucleotide sequences encoding the polypeptides can be obtained ina number of ways, such as through random mutagenesis and randompolynucleotide synthesis. These random peptide display libraries can beused to screen for peptides that interact with a known target that canbe a protein or polypeptide, such as a ligand or receptor, a biologicalor synthetic macromolecule, or organic or inorganic substances.Techniques for creating and screening such random peptide displaylibraries are known in the art (Ladner et al., U.S. Pat. No. 5,223,409;Ladner et al., U.S. Pat. No. 4,946,778; Ladner et al., U.S. Pat. No.5,403,484 and Ladner et al., U.S. Pat. No. 5,571,698) and random peptidedisplay libraries and kits for screening such libraries are availablecommercially, for instance from Clontech (Palo Alto, Calif.), InvitrogenInc. (San Diego, Calif.), New England Biolabs, Inc. (Beverly, Mass.) andPharmacia LKB Biotechnology Inc. (Piscataway, N.J.). Random peptidedisplay libraries can be screened using the soluble IL-22RA receptorpolypeptides or fragments thereof, such as antigenic epitope polypeptidesequences disclosed herein to identify proteins which bind toIL-22RA-comprising receptor polypeptides. These “binding polypeptides,”which interact with soluble IL-22RA-comprising receptor polypeptides,can be used for tagging cells; for isolating homolog polypeptides byaffinity purification; they can be directly or indirectly conjugated todrugs, toxins, radionuclides and the like. These binding polypeptidescan also be used in analytical methods such as for screening expressionlibraries and neutralizing activity, e.g., for binding, blocking,inhibiting, reducing, antagonizing or neutralizing interaction betweenIL-22 ligand and receptor, or viral binding to a receptor. The bindingpolypeptides can also be used for diagnostic assays for determiningcirculating levels of soluble IL-22RA-comprising receptor polypeptides;for detecting or quantitating soluble or non-soluble IL-22RA-comprisingreceptors as marker of underlying pathology or disease. These bindingpolypeptides can also act as “antagonists” to block or inhibit solubleor membrane-bound IL-22RA monomeric receptor or IL-22RA homodimeric,heterodimeric or multimeric polypeptide binding (e.g. to ligand) andsignal transduction in vitro and in vivo. Again, these bindingpolypeptides serve as anti-IL-22RA monomeric receptor or anti-IL-22RAhomodimeric, heterodimeric or multimeric polypeptides and are useful forinhibiting IL-22 or both IL-20 and IL-22 activity, as well as receptoractivity or protein-binding. Antibodies raised to the natural receptorcomplexes of the present invention, and IL-22RA-epitope-bindingantibodies, and anti-IL-22RA neutralizing monoclonal antibodies may bepreferred embodiments, as they may act more specifically against theIL-22RA and can inhibit IL-22 or both IL-20 and IL-22. Moreover, theantagonistic and binding activity of the antibodies of the presentinvention can be assayed in an IL-20 or IL-22 proliferation, signaltrap, luciferase or binding assays in the presence of IL-20 or IL-22respectively, and IL-22RA-comprising soluble receptors, and otherbiological or biochemical assays described herein.

Antibodies to soluble IL-22RA receptor polypeptides (e.g., antibodies toSEQ ID NO:3) or fragments thereof, such as antigenic epitopes may beused for inhibiting the inflammatory effects of IL-20, IL-22, or bothIL-20 and IL-22 in vivo, for therapeutic use against psoriasis, atopicdermatitis, inflammatory skin conditions, endotoxemia, arthritis,asthma, IBD, colitis, psoriatic arthritis, rheumatoid arthritis or otherIL-20 and IL-22-induced inflammatory conditions; tagging cells thatexpress IL-22RA receptors; for isolating soluble IL-22RA-comprisingreceptor polypeptides by affinity purification; for diagnostic assaysfor determining circulating levels of soluble IL-22RA-comprisingreceptor polypeptides; for detecting or quantitating solubleIL-22RA-comprising receptors as marker of underlying pathology ordisease; in analytical methods employing FACS; for screening expressionlibraries; for generating anti-idiotypic antibodies that can act asIL-22 or IL-20 agonists; and as neutralizing antibodies or asantagonists to bind, block, inhibit, reduce, or antagonize IL-22RAreceptor function, or to bind, block, inhibit, reduce, antagonize orneutralize IL-22 and/or IL-20 activity (either individually or together)in vitro and in vivo. Suitable direct tags or labels includeradionuclides, enzymes, substrates, cofactors, biotin, inhibitors,fluorescent markers, chemiluminescent markers, magnetic particles andthe like; indirect tags or labels may feature use of biotin-avidin orother complement/anti-complement pairs as intermediates. Antibodiesherein may also be directly or indirectly conjugated to drugs, toxins,radionuclides and the like, and these conjugates used for in vivodiagnostic or therapeutic applications. Moreover, antibodies to solubleIL-22RA-comprising receptor polypeptides, or fragments thereof may beused in vitro to detect denatured or non-denatured IL-22RA-comprisingreceptor polypeptides or fragments thereof in assays, for example,Western Blots or other assays known in the art.

Antibodies to soluble IL-22RA receptor or soluble IL-22RA homodimeric,heterodimeric or multimeric receptor polypeptides are useful for taggingcells that express the corresponding receptors and assaying theirexpression levels, for affinity purification, within diagnostic assaysfor determining circulating levels of receptor polypeptides, analyticalmethods employing fluorescence-activated cell sorting. Moreover,divalent antibodies, and anti-idiotypic antibodies may be used asagonists to mimic the effect of the IL-22RA ligand, IL-22 or IL-20.

Antibodies herein can also be directly or indirectly conjugated todrugs, toxins, radionuclides and the like, and these conjugates used forin vivo diagnostic or therapeutic applications. For instance, antibodiesor binding polypeptides which recognize soluble IL-22RA receptor orsoluble IL-22RA homodimeric, heterodimeric or multimeric receptorpolypeptides can be used to identify or treat tissues or organs thatexpress a corresponding anti-complementary molecule (i.e., aIL-22RA-comprising soluble or membrane-bound receptor). Morespecifically, antibodies to soluble IL-22RA-comprising receptorpolypeptides, or bioactive fragments or portions thereof, can be coupledto detectable or cytotoxic molecules and delivered to a mammal havingcells, tissues or organs that express the IL-22RA-comprising receptorsuch as IL-22RA-expressing cancers.

Suitable detectable molecules may be directly or indirectly attached topolypeptides that bind IL-22RA-comprising receptor polypeptides, such as“binding polypeptides,” (including binding peptides disclosed above),antibodies, or bioactive fragments or portions thereof. Suitabledetectable molecules include radionuclides, enzymes, substrates,cofactors, inhibitors, fluorescent markers, chemiluminescent markers,magnetic particles and the like. Suitable cytotoxic molecules may bedirectly or indirectly attached to the polypeptide or antibody, andinclude bacterial or plant toxins (for instance, diphtheria toxin,Pseudomonas exotoxin, ricin, abrin and the like), as well as therapeuticradionuclides, such as iodine-131, rhenium-188 or yttrium-90 (eitherdirectly attached to the polypeptide or antibody, or indirectly attachedthrough means of a chelating moiety, for instance). Binding polypeptidesor antibodies may also be conjugated to cytotoxic drugs, such asadriamycin. For indirect attachment of a detectable or cytotoxicmolecule, the detectable or cytotoxic molecule can be conjugated with amember of a complementary/anticomplementary pair, where the other memberis bound to the binding polypeptide or antibody portion. For thesepurposes, biotin/streptavidin is an exemplarycomplementary/anticomplementary pair.

In another embodiment, binding polypeptide-toxin fusion proteins orantibody-toxin fusion proteins can be used for targeted cell or tissueinhibition or ablation (for instance, to treat cancer cells or tissues).Alternatively, if the binding polypeptide has multiple functionaldomains (i.e., an activation domain or a ligand binding domain, plus atargeting domain), a fusion protein including only the targeting domainmay be suitable for directing a detectable molecule, a cytotoxicmolecule or a complementary molecule to a cell or tissue type ofinterest. In instances where the fusion protein including only a singledomain includes a complementary molecule, the anti-complementarymolecule can be conjugated to a detectable or cytotoxic molecule. Suchdomain-complementary molecule fusion proteins thus represent a generictargeting vehicle for cell/tissue-specific delivery of genericanti-complementary-detectable/cytotoxic molecule conjugates.

In another embodiment, IL-22RA binding polypeptide-cytokine orantibody-cytokine fusion proteins can be used for enhancing in vivokilling of target tissues (for example, spleen, pancreatic, blood,lymphoid, colon, and bone marrow cancers), if the bindingpolypeptide-cytokine or anti-IL-22RA receptor antibody targets thehyperproliferative cell (See, generally, Hornick et al., Blood89:4437-47, 1997). The described fusion proteins enable targeting of acytokine to a desired site of action, thereby providing an elevatedlocal concentration of cytokine. Suitable anti-IL-22RA monomer,homodimer, heterodimer or multimer antibodies target an undesirable cellor tissue (i.e., a tumor or a leukemia), and the fused cytokine mediatesimproved target cell lysis by effector cells. Suitable cytokines forthis purpose include interleukin 2 and granulocyte-macrophagecolony-stimulating factor (GM-CSF), for instance.

Alternatively, IL-22RA receptor binding polypeptides or antibody fusionproteins described herein can be used for enhancing in vivo killing oftarget tissues by directly stimulating a IL-22RA receptor-modulatedapoptotic pathway, resulting in cell death of hyperproliferative cellsexpressing IL-22RA-comprising receptors.

10. Therapeutic Uses of Polypeptides Having IL-22RA Activity orAntibodies to IL-22RA

Amino acid sequences having soluble IL-22RA activity can be used tomodulate the immune system by binding IL-22RA ligands IL-20 and IL-22(either singly or together), and thus, preventing the binding of IL-22RAligand with endogenous IL-22RA receptor. IL-22RA antagonists, such asanti-IL-22RA antibodies, can also be used to modulate the immune systemby inhibiting the binding of IL-22RA ligand with the endogenous IL-22RAreceptor. Accordingly, the present invention includes the use ofproteins, polypeptides, and peptides having IL-22RA activity (such assoluble IL-22RA polypeptides, IL-22RA polypeptide fragments, IL-22RAanalogs (e.g., anti-IL-22RA anti-idiotype antibodies), and IL-22RAfusion proteins) to a subject which lacks an adequate amount of thispolypeptide, or which produces an excess of IL-22RA ligand. IL-22RAantagonists (e.g., anti-IL-22RA antibodies) can be also used to treat asubject which produces an excess of either IL-22RA ligand or IL-22RA.Suitable subjects include mammals, such as humans. For example, suchIL-22RA polypeptides and anti-IL-22RA antibodies are useful in binding,blocking, inhibiting, reducing, antagonizing or neutralizing IL-20 andIL-22 (either singly or together), in the treatment of psoriasis, atopicdermatitis, inflammatory skin conditions, psoriatic arthritis,arthritis, endotoxemia, asthma, inflammatory bowel disease (IBD),colitis, and other inflammatory conditions disclosed herein.

Moreover, we have shown that the IL-22RA receptor binds a ligand calledT-cell inducible Factor (IL-22) (SEQ ID NO:6; Dumoutier, L. et al.,Proc. Nat'l. Acad. Sci. 97:10144-10149, 2000; mouse IL-22 sequence isshown in Dumontier et al., J. Immunol. 164:1814-1819, 2000). Moreover,commonly owned zcytor11 (IL-22RA) (U.S. Pat. No. 5,965,704) and CRF2-4receptor also bind IL-22 as a heterodimer (See, WIPO publication WO00/24758; Dumontier et al., J. Immunol. 164:1814-1819, 2000; Spencer, SD et al., J. Exp. Med. 187:571-578, 1998; Gibbs, V C and Pennica Gene186:97-101, 1997 (CRF2-4 cDNA); Xie, M H et al., J. Biol. Chem. 275:31335-31339, 2000; and Kotenko, S V et al., J. Biol. Chem.276:2725-2732, 2001). Moreover, IL-10β receptor may be involved as areceptor for IL-22, and it is believed to be synonymous with CRF2-4(Dumoutier, L. et al., Proc. Nat'l. Acad. Sci. 97:10144-10149, 2000; LiuY et al, J. Immunol. 152; 1821-1829, 1994 (IL-10R cDNA). Moreover, wehave shown that IL-22RA receptor binds a ligand called IL-20 (SEQ IDNO:8; WIPO Publication No. WO 99/27103). Within preferred embodiments,the soluble receptor form of IL-22RA, SEQ ID NO:3) is a monomer,homodimer, heterodimer, or multimer that binds to, blocks, inhibits,reduces, antagonizes or neutralizes IL-22 and IL-20 in vivo. Antibodiesand binding polypeptides to such IL-22RA monomer, homodimer,heterodimer, or multimers also serve as antagonists of IL-22RA activity,and as IL-20 and IL-22 antagonists (singly or together), as describedherein.

In addition, we have described herein, and have demonstrated that bothpolyclonal and monoclonal neutralizing anti-IL-22 antibodies bind to,block, inhibit, reduce, antagonize or neutralize IL-22 and IL-20activity in cell based neutralization assays.

IL-22 has been shown to be induced in the presence of IL-9, and issuspected to be involved in promoting Th1-type immune responses, andinflammation. IL-9 stimulates proliferation, activation, differentiationand/or induction of immune function in a variety of ways and isimplicated in asthma, lung mastocytosis, and other diseases, as well asactivates STAT pathways. Antagonists of IL-22 or IL-9 function can havebeneficial use against such human diseases. The present inventionprovides such novel antagonists of IL-22.

IL-22 has been show to be involved in up-regulate the production ofacute phase reactants, such as serum amyloid A (SAA),α1-antichymotrypsin, and haptoglobin, and that IL-22 expression isincreased upon injection of lipopolysaccharide (LPS) in vivo suggestingthat IL-22 is involved in inflammatory response (Dumoutier, L. et al.,Proc. Nat'l. Acad. Sci. 97:10144-10149, 2000). Production of acute phaseproteins, such as SAA, is considered s short-term survival mechanismwhere inflammation is beneficial; however, maintenance of acute phaseproteins for longer periods contributes to chronic inflammation and canbe harmful to human health. For review, see Uhlar, C M and Whitehead, AS, Eur. J. Biochem. 265:501-523, 1999, and Baumann H. and Gauldie, J.Immunology Today 15:74-80, 1994. Moreover, the acute phase protein SAAis implicated in the pathogenesis of several chronic inflammatorydiseases, is implicated in atherosclerosis and rheumatoid arthritis, andis the precursor to the amyloid A protein deposited in amyloidosis(Uhlar, C M and Whitehead, supra.). Thus, as IL-22 acts as apro-inflammatory molecule and induces production of SAA, antagonistswould be useful in treating inflammatory disease and other diseasesassociated with acute phase response proteins induced by IL-22. Suchantagonists are provided by the present invention. For example, methodof reducing IL-22-induced or IL-9 induced inflammation comprisesadministering to a mammal with inflammation an amount of a compositionof soluble IL-22RA-comprising receptor sufficient to reduceinflammation. Moreover, a method of suppressing an inflammatory responsein a mammal with inflammation can comprise: (1) determining a level ofserum amyloid A protein; (2) administering a composition comprising asoluble IL-22RA cytokine receptor polypeptide as described herein in anacceptable pharmaceutical vehicle; (3) determining a post administrationlevel of serum amyloid A protein; (4) comparing the level of serumamyloid A protein in step (1) to the level of serum amyloid A protein instep (3), wherein a lack of increase or a decrease in serum amyloid Aprotein level is indicative of suppressing an inflammatory response.Experimental evidence described herein shows that IL-22 antagonists,such as soluble receptors and antibodies, indeed reduce SAA levels in invivo models for inflammatory diseases, showing that binding, blocking,inhibiting, reducing, antagonizing or neutralizing IL-22 hasanti-inflammatory effects.

Evidence indicates that a role IL-20 and its receptors are involved inpsoriasis. This multigenic skin disease is characterized by increasedkeratinocyte proliferation, altered keratinocyte differentiation, andinfiltration of immune cells into the skin. The first line of evidencefor a role of IL-20 in psoriasis is that the observed hyperkeratosis andthickened epidermis in the transgenic mice that resemble human psoriaticabnormalities. Decreased numbers of tonofilaments, thought to be relatedto defective keratinization, are a striking feature of human psoriasis.Intramitochondrial inclusions have been found in both chemically inducedand naturally occurring hyperplastic skin conditions in mice. The causeof the inclusions and their effects on mitochondrial function, if any,are unknown. IL-20 transgenic mice exhibit many of the characteristicsobserved in human psoriasis.

Moreover, IL-20 receptor mRNA (both IL-20RA and IL-20RB mRNA) aremarkedly upregulated in human psoriatic skin compared to normal skinfurther suggesting a role for IL-20 in psoriasis. Both IL-20 receptorsubunits are expressed in keratinocytes throughout the epidermis and arealso expressed in a subset of immune and endothelial cells. We proposethat increased expression of an activated IL-20 receptor may alter theinteractions between endothelial cells, immune cells and keratinocytes,leading to dysregulation of keratinocyte proliferation anddifferentiation. In addition, mouse knockout data described herein,wherein the IL-22RA receptor is knocked out, show that IL-22RA wasnecessary for the IL-20-induced inflammatory effects in skin intransgenic animals. These results provided evidence that effectivelyblocking IL-22RA activity, for example via an IL-22RA gene knockout, orsimilarly via a neutralizing monoclonal antibody to IL-22RA of thepresent invention, would similarly reduce IL-20-induced skin effects, aswell as IL-22-induced skin effects, for example in psoriasis, IBD,colitis, or other inflammatory diseases induced by IL-20, and or IL-22including IBD, arthritis, asthma, psoriatic arthritis, colitis,inflammatory skin conditions, and atopic dermatitis.

Moreover, IL-20 stimulates signal transduction in the human keratinocyteHaCaT cell line, supporting a direct action of this novel ligand inskin. In addition, IL-1β, EGF and TNF-α, proteins known to be active inkeratinocytes and to be involved with proliferative and pro-inflammatorysignals in skin, enhance the response to IL-20. In both HaCaT and BHKcells expressing the IL-20 receptor, IL-20 signals through STAT3.

As indicated in the discussion above and the examples below, IL-20 isinvolved in the pathology of psoriasis. The present invention is inparticular a method for treating psoriasis by administering agents thatbind, block, inhibit, reduce, antagonize or neutralize IL-20. Theantagonists to IL-20 can either be a soluble receptor that binds toIL-20, such a soluble IL-22RA, or antibodies, single chain antibodies orfragments of antibodies that bind to either IL-20 or the IL-20 receptor,e.g., anti-IL-22RA antibodies. The antagonists will thus preventactivation of the IL-20 receptor. Moreover, because IL-20 and IL-22share IL-22RA as a common receptor, antagonists such as soluble IL-22RA,or antibodies, single chain antibodies or fragments of antibodies thatbind to IL-22RA receptor can be used to concurrently bind to, block,inhibit, reduce, antagonize or neutralize IL-22 or both IL-20 and IL-22activity.

Psoriasis is one of the most common dermatologic diseases, affecting upto 1 to 2 percent of the world's population. It is a chronicinflammatory skin disorder characterized by erythematous, sharplydemarcated papules and rounded plaques, covered by silvery micaceousscale. The skin lesions of psoriasis are variably pruritic. Traumatizedareas often develop lesions of psoriasis. Additionally, other externalfactors may exacerbate psoriasis including infections, stress, andmedications, e.g. lithium, beta blockers, and anti-malarials.

The most common variety of psoriasis is called plaque type. Patientswith plaque-type psoriasis will have stable, slowly growing plaques,which remain basically unchanged for long periods of time. The mostcommon areas for plaque psoriasis to occur are the elbows knees, glutealcleft, and the scalp. Involvement tends to be symmetrical. Inversepsoriasis affects the intertriginous regions including the axilla,groin, submammary region, and navel, and it also tends to affect thescalp, palms, and soles. The individual lesions are sharply demarcatedplaques but may be moist due to their location. Plaque-type psoriasisgenerally develops slowly and runs an indolent course. It rarelyspontaneously remits.

Eruptive psoriasis (guttate psoriasis) is most common in children andyoung adults. It develops acutely in individuals without psoriasis or inthose with chronic plaque psoriasis. Patients present with many smallerythematous, scaling papules, frequently after upper respiratory tractinfection with beta-hemolytic streptococci. Patients with psoriasis mayalso develop pustular lesions. These may be localized to the palms andsoles or may be generalized and associated with fever, malaise,diarrhea, and arthralgias.

About half of all patients with psoriasis have fingernail involvement,appearing as punctate pitting, nail thickening or subungualhyperkeratosis. About 5 to 10 percent of patients with psoriasis haveassociated joint complaints, and these are most often found in patientswith fingernail involvement. Although some have the coincidentoccurrence of classic Although some have the coincident occurrence ofclassic rheumatoid arthritis, many have joint disease that falls intoone of five type associated with psoriasis: (1) disease limited to asingle or a few small joints (70 percent of cases); (2) a seronegativerheumatoid arthritis-like disease; (3) involvement of the distalinterphalangeal joints; (4) severe destructive arthritis with thedevelopment of “arthritis mutilans”; and (5) disease limited to thespine.

Psoriasis can be treated by administering agents that bind to, block,inhibit, reduce, antagonize or neutralize to IL-22, IL-20, or both IL-20and IL-22. The preferred antagonists are either a soluble receptor toIL-20 and IL-22, such as IL-22RA (SEQ ID NO:3) or antibodies, antibodyfragments or single chain antibodies that bind to the IL-22RA receptor,such as the neutralizing antibodies of the present invention. Suchantagonists can be administered alone or in combination with otherestablished therapies such as lubricants, keratolytics, topicalcorticosteroids, topical vitamin D derivatives, anthralin, systemicantimetabolites such as methotrexate, psoralen-ultraviolet-light therapy(PUVA), etretinate, isotretinoin, cyclosporine, and the topical vitaminD3 derivative calcipotriol. Moreover, such antagonists can beadministered to individual subcutaneously, intravenously, ortransdermally using a cream or transdermal patch that contains theantagonist. If administered subcutaneously, the antagonist can beinjected into one or more psoriatic plaques. If administeredtransdermally, the antagonists can be administered directly on theplaques using a cream, ointment, salve, or solution containing theantagonist.

Antagonists to IL-20 or IL-22 can be administered to a person who hasasthma, bronchitis or cystic fibrosis or other inflammatory lung diseaseto treat the disease. The antagonists can be administered by anysuitable method including intravenous, subcutaneous, bronchial lavage,and the use of inhalant containing the antagonist.

Analysis of the tissue distribution of the mRNA corresponding IL-22RAcDNA showed that mRNA level was highest in placenta and spleen, and theligand to which IL-22RA binds (IL-22) is implicated in inducinginflammatory response including induction of the acute-phase response(Dumoutier, L. et al., Proc. Nat'l. Acad. Sci. 97:10144-10149, 2000).Thus, particular embodiments of the present invention are directedtoward use of soluble IL-22RA and anti-IL-22RA antibodies as antagonistsin inflammatory and immune diseases or conditions such as psoriasis,psoriatic arthritis, atopic dermatitis, inflammatory skin conditions,rheumatoid arthritis, inflammatory bowel disease (IBD), Crohn's Disease,diverticulosis, asthma, pancreatitis, type I diabetes (IDDM), pancreaticcancer, pancreatitis, Graves Disease, colon and intestinal cancer,autoimmune disease, sepsis, organ or bone marrow transplant;inflammation due to endotoxemia, trauma, sugery or infection;amyloidosis; splenomegaly; graft versus host disease; and whereinhibition of inflammation, immune suppression, reduction ofproliferation of hematopoietic, immune, inflammatory or lymphoid cells,macrophages, T-cells (including Th1 and Th2 cells), suppression ofimmune response to a pathogen or antigen, or other instances whereinhibition of IL-22 or IL-20 cytokines is desired.

Moreover, antibodies or binding polypeptides that bind IL-22RApolypeptides described herein, and IL-22RA polypeptides themselves areuseful to:

1) Block, inhibit, reduce, antagonize or neutralize signaling via IL-20or IL-22 receptors in the treatment of acute inflammation, inflammationas a result of trauma, tissue injury, surgery, sepsis or infection, andchronic inflammatory diseases such as asthma, inflammatory bowel disease(IBD), chronic colitis, splenomegaly, rheumatoid arthritis, recurrentacute inflammatory episodes (e.g., tuberculosis), and treatment ofamyloidosis, and atherosclerosis, Castleman's Disease, asthma, and otherdiseases associated with the induction of acute-phase response.

2) Block, inhibit, reduce, antagonize or neutralize signaling via IL-20or IL-22 receptors in the treatment of autoimmune diseases such as IDDM,multiple sclerosis (MS), systemic Lupus erythematosus (SLE), myastheniagravis, rheumatoid arthritis, and IBD to prevent or inhibit signaling inimmune cells (e.g. lymphocytes, monocytes, leukocytes) via IL-22RA(Hughes C et al., J. Immunol 153: 3319-3325, 1994). Alternativelyantibodies, such as monoclonal antibodies (MAb) to IL-22RA-comprisingreceptors, can also be used as an antagonist to deplete unwanted immunecells to treat autoimmune disease. Asthma, allergy and other atopicdisease may be treated with an MAb against, for example, soluble IL-22RAsoluble receptors to inhibit the immune response or to deplete offendingcells. Blocking, inhibiting, reducing, or antagonizing signaling viaIL-22RA, using the polypeptides and antibodies of the present invention,may also benefit diseases of the pancreas, kidney, pituitary andneuronal cells. IDDM, NIDDM, pancreatitis, and pancreatic carcinoma maybenefit. IL-22RA may serve as a target for MAb therapy of cancer wherean antagonizing MAb inhibits cancer growth and targets immune-mediatedkilling. (Holliger P, and Hoogenboom, H: Nature Biotech. 16: 1015-1016,1998). Mabs to soluble IL-22RA may also be useful to treat nephropathiessuch as glomerulosclerosis, membranous neuropathy, amyloidosis (whichalso affects the kidney among other tissues), renal arteriosclerosis,glomerulonephritis of various origins, fibroproliferative diseases ofthe kidney, as well as kidney dysfunction associated with SLE, IDDM,type II diabetes (NIDDM), renal tumors and other diseases.

3) Agonize, enhance, increase or initiate signaling via IL-20 or IL-22receptors in the treatment of autoimmune diseases such as IDDM, MS, SLE,myasthenia gravis, rheumatoid arthritis, and IBD. Anti-IL-22RAneutralizing and monoclonal antibodies may signal lymphocytes or otherimmune cells to differentiate, alter proliferation, or change productionof cytokines or cell surface proteins that ameliorate autoimmunity.Specifically, modulation of a T-helper cell response to an alternatepattern of cytokine secretion may deviate an autoimmune response toameliorate disease (Smith J A et al., J. Immunol. 160:4841-4849, 1998).Similarly, agonistic Anti-soluble IL-22RA, anti-soluble IL-22RA/CRF2-4heterodimers and multimer monoclonal antibodies may be used to signal,deplete and deviate immune cells involved in asthma, allergy and atopoicdisease. Signaling via IL-22RA may also benefit diseases of thepancreas, kidney, pituitary and neuronal cells. IDDM, NIDDM,pancreatitis, and pancreatic carcinoma may benefit. IL-22RA may serve asa target for MAb therapy of pancreatic cancer where a signaling MAbinhibits cancer growth and targets immune-mediated killing (Tutt, A L etal., J. Immunol. 161: 3175-3185, 1998). Similarly renal cell carcinomamay be treated with monoclonal antibodies to IL-22RA-comprising solublereceptors of the present invention.

Soluble IL-22RA polypeptides described herein can be used to bind,block, inhibit, reduce, antagonize or neutralize IL-22 or IL-20activity, either singly or together, in the treatment of autoimmunedisease, atopic disease, NIDDM, pancreatitis and kidney dysfunction asdescribed above. A soluble form of IL-22RA may be used to promote anantibody response mediated by Th cells and/or to promote the productionof IL-4 or other cytokines by lymphocytes or other immune cells.

The soluble IL-22RA-comprising receptors of the present invention areuseful as antagonists of IL-20 or IL-22 cytokine. Such antagonisticeffects can be achieved by direct neutralization or binding of IL-20 orIL-22. In addition to antagonistic uses, the soluble receptors of thepresent invention can bind IL-22 and act as carrier proteins for IL-20or IL-22 cytokine, in order to transport the Ligand to differenttissues, organs, and cells within the body. As such, the solublereceptors of the present invention can be fused or coupled to molecules,polypeptides or chemical moieties that direct thesoluble-receptor-Ligand complex to a specific site, such as a tissue,specific immune cell, or tumor. For example, in acute infection or somecancers, benefit may result from induction of inflammation and localacute phase response proteins by the action of IL-22. Thus, the solublereceptors of the present invention can be used to specifically directthe action of IL-20 or IL-22. See, Cosman, D. Cytokine 5: 95-106, 1993;and Fernandez-Botran, R. Exp. Opin. Invest. Drugs 9:497-513, 2000.

Moreover, the soluble receptors of the present invention can be used tostabilize the IL-22 or IL-20, to increase the bioavailability,therapeutic longevity, and/or efficacy of the Ligand by stabilizing theLigand from degradation or clearance, or by targeting the ligand to asite of action within the body. For example the naturally occurringIL-6/soluble IL-6R complex stabilizes IL-6 and can signal through thegp130 receptor. See, Cosman, D. supra., and Fernandez-Botran, R. supra.Moreover, IL-22RA may be combined with a cognate ligand such as IL-22 tocomprise a ligand/soluble receptor complex. Such complexes may be usedto stimulate responses from cells presenting a companion receptorsubunit such as, for example, pDIRS1 (IL-20RB) or CRF2-4 (IL-10RB). Thecell specificity of IL-22RA/ligand complexes may differ from that seenfor the ligand administered alone. Furthermore the complexes may havedistinct pharmacokinetic properties such as affecting half-life,dose/response and organ or tissue specificity. IL-22RA/IL-22 orIL-22RA/IL-20 complexes thus may have agonist activity to enhance animmune response or stimulate mesangial cells or to stimulate hepaticcells. Alternatively only tissues expressing a signaling subunit theheterodimerizes with the complex may be affected analogous to theresponse to IL6/IL6R complexes (Hirota H. et al., Proc. Nat'l. Acad.Sci. 92:4862-4866, 1995; Hirano, T. in Thomason, A. (Ed.) “The CytokineHandbook”, 3^(rd) Ed., p. 208-209). Soluble receptor/cytokine complexesfor IL12 and CNTF display similar activities.

Moreover Inflammation is a protective response by an organism to fendoff an invading agent. Inflammation is a cascading event that involvesmany cellular and humoral mediators. On one hand, suppression ofinflammatory responses can leave a host immunocompromised; however, ifleft unchecked, inflammation can lead to serious complications includingchronic inflammatory diseases (e.g., psoriasis, arthritis, rheumatoidarthritis, multiple sclerosis, inflammatory bowel disease and the like),septic shock and multiple organ failure. Importantly, these diversedisease states share common inflammatory mediators. The collectivediseases that are characterized by inflammation have a large impact onhuman morbidity and mortality. Therefore it is clear thatanti-inflammatory proteins, such as IL-22RA, and anti-IL-22RAantibodies, could have crucial therapeutic potential for a vast numberof human and animal diseases, from asthma and allergy to autoimmunityand septic shock.

1. Arthritis

Arthritis, including osteoarthritis, rheumatoid arthritis, arthriticjoints as a result of injury, and the like, are common inflammatoryconditions which would benefit from the therapeutic use ofanti-inflammatory proteins, such as IL-22RA polypeptides of the presentinvention. For example, rheumatoid arthritis (RA) is a systemic diseasethat affects the entire body and is one of the most common forms ofarthritis. It is characterized by the inflammation of the membranelining the joint, which causes pain, stiffness, warmth, redness andswelling. Inflammatory cells release enzymes that may digest bone andcartilage. As a result of rheumatoid arthritis, the inflamed jointlining, the synovium, can invade and damage bone and cartilage leadingto joint deterioration and severe pain amongst other physiologiceffects. The involved joint can lose its shape and alignment, resultingin pain and loss of movement.

Rheumatoid arthritis (RA) is an immune-mediated disease particularlycharacterized by inflammation and subsequent tissue damage leading tosevere disability and increased mortality. A variety of cytokines areproduced locally in the rheumatoid joints. Numerous studies havedemonstrated that IL-1 and TNF-alpha, two prototypic pro-inflammatorycytokines, play an important role in the mechanisms involved in synovialinflammation and in progressive joint destruction. Indeed, theadministration of TNF-alpha and IL-1 inhibitors in patients with RA hasled to a dramatic improvement of clinical and biological signs ofinflammation and a reduction of radiological signs of bone erosion andcartilage destruction. However, despite these encouraging results, asignificant percentage of patients do not respond to these agents,suggesting that other mediators are also involved in the pathophysiologyof arthritis (Gabay, Expert. Opin. Biol. Ther. 2(2):135-149, 2002). Oneof those mediators could be IL-20 or IL-22, and as such a molecule thatbinds or inhibits IL-22 or IL-20 activity, such as IL-22RA polypeptides,or anti IL-22RA antibodies or binding partners, could serve as avaluable therapeutic to reduce inflammation in rheumatoid arthritis, andother arthritic diseases.

There are several animal models for rheumatoid arthritis known in theart. For example, in the collagen-induced arthritis (CIA) model, micedevelop chronic inflammatory arthritis that closely resembles humanrheumatoid arthritis. Since CIA shares similar immunological andpathological features with RA, this makes it an ideal model forscreening potential human anti-inflammatory compounds. The CIA model isa well-known model in mice that depends on both an immune response, andan inflammatory response, in order to occur. The immune responsecomprises the interaction of B-cells and CD4+ T-cells in response tocollagen, which is given as antigen, and leads to the production ofanti-collagen antibodies. The inflammatory phase is the result of tissueresponses from mediators of inflammation, as a consequence of some ofthese antibodies cross-reacting to the mouse's native collagen andactivating the complement cascade. An advantage in using the CIA modelis that the basic mechanisms of pathogenesis are known. The relevantT-cell and B-cell epitopes on type II collagen have been identified, andvarious immunological (e.g., delayed-type hypersensitivity andanti-collagen antibody) and inflammatory (e.g., cytokines, chemokines,and matrix-degrading enzymes) parameters relating to immune-mediatedarthritis have been determined, and can thus be used to assess testcompound efficacy in the CIA model (Wooley, Curr. Opin. Rheum. 3:407-20,1999; Williams et al., Immunol. 89:9784-788, 1992; Myers et al., LifeSci. 61:1861-78, 1997; and Wang et al., Immunol. 92:8955-959, 1995).

The administration of soluble IL-22RA2 comprising polypeptides(zcytor16), such as zcytor16-Fc4 or other IL-22RA2 soluble and fusionproteins to these CIA model mice was used to evaluate the use ofIL-22RA2 as an antagonist to IL-22 used to ameliorate symptoms and alterthe course of disease. Moreover, the results showing inhibition of IL-22by IL-22RA2 provide proof of concept that other IL-22 antagonists, suchas IL-22RA or antibodies thereto, can also be used to amelioratesymptoms and alter the course of disease. Since the ligand of IL-22RA2,IL-22, induces production of SAA, which is implicated in thepathogenesis of rheumatoid arthritis, and IL-22RA2 was demonstrated tobe able to inhibit IL-22 and SAA activity in vitro and in vivo, thesystemic or local administration of IL-22RA2 comprising polypeptides,such as zcytor16-Fc4 or other IL-22 soluble receptors (e.g., IL-22RA;SEQ ID NO:3) and anti-IL-22RA antibodies, and fusion proteins canpotentially suppress the inflammatory response in RA. The injection of10 ug zcytor16-Fc (three times a week for 4 weeks) significantly reducedthe disease score (paw score, incident of inflammation or disease).Other potential therapeutics include IL-22RA polypeptides, anti-IL-22RAantibodies, or anti IL-22 antibodies or binding partners, and the like.

One group has shown that an anti-mouse IL-22 antibody may reducesymptoms in a mouse CIA-model relative to control mice, thus showingconceptually that soluble IL-22RA polypeptides and neutralizingantibodies to IL-22RA may be beneficial in treating human disease. Theadministration of a single mouse-IL-22-specific rat monoclonal antibody(P3/1) reduced the symptoms of arthritis in the animals when introducedprophylactically or after CIA-induced arthritis was induced in the model(WIPO Publication 02/068476; published Sep. 9, 2002). Therefore, thesoluble IL-22RA polypeptides and anti-IL-22RA antibodies of the presentinvention, including the neutralizing anti-human IL-22RA antibodies ofthe present invention, can be used to neutralize IL-22 and IL-20 in thetreatment of specific human diseases such as psoriasis, psoriaticarthritis, arthritis, endotoxemia, inflammatory bowel disease (IBD),colitis, and other inflammatory conditions disclosed herein.

2. Endotoxemia

Endotoxemia is a severe condition commonly resulting from infectiousagents such as bacteria and other infectious disease agents, sepsis,toxic shock syndrome, or in immunocompromised patients subjected toopportunistic infections, and the like. Therapeutically useful ofanti-inflammatory proteins, such as IL-22RA polypeptides and antibodiesof the present invention, could aid in preventing and treatingendotoxemia in humans and animals. IL-22RA polypeptides, anti-IL22RAantibodies, or anti IL-22 antibodies or binding partners, could serve asa valuable therapeutic to reduce inflammation and pathological effectsin endotoxemia.

Lipopolysaccharide (LPS) induced endotoxemia engages many of theproinflammatory mediators that produce pathological effects in theinfectious diseases and LPS induced endotoxemia in rodents is a widelyused and acceptable model for studying the pharmacological effects ofpotential pro-inflammatory or immunomodulating agents. LPS, produced ingram-negative bacteria, is a major causative agent in the pathogenesisof septic shock (Glausner et al., Lancet 338:732, 1991). A shock-likestate can indeed be induced experimentally by a single injection of LPSinto animals. Molecules produced by cells responding to LPS can targetpathogens directly or indirectly. Although these biological responsesprotect the host against invading pathogens, they may also cause harm.Thus, massive stimulation of innate immunity, occurring as a result ofsevere Gram-negative bacterial infection, leads to excess production ofcytokines and other molecules, and the development of a fatal syndrome,septic shock syndrome, which is characterized by fever, hypotension,disseminated intravascular coagulation, and multiple organ failure(Dumitru et al. Cell 103:1071-1083, 2000).

These toxic effects of LPS are mostly related to macrophage activationleading to the release of multiple inflammatory mediators. Among thesemediators, TNF appears to play a crucial role, as indicated by theprevention of LPS toxicity by the administration of neutralizinganti-TNF antibodies (Beutler et al., Science 229:869, 1985). It is wellestablished that 1 ug injection of E. coli LPS into a C57B1/6 mouse willresult in significant increases in circulating IL-6, TNF-alpha, IL-1,and acute phase proteins (for example, SAA) approximately 2 hours postinjection. The toxicity of LPS appears to be mediated by these cytokinesas passive immunization against these mediators can result in decreasedmortality (Beutler et al., Science 229:869, 1985). The potentialimmunointervention strategies for the prevention and/or treatment ofseptic shock include anti-TNF mAb, IL-1 receptor antagonist, LIF, IL-10,and G-CSF.

The administration of soluble IL-22RA2 comprising polypeptides, such asZcytor16-Fc4 or other IL-22RA soluble and fusion proteins to theseLPS-induced model was used to evaluate the use of IL-22RA2 to amelioratesymptoms and alter the course of LPS-induced disease. Moreover, theresults showing inhibition of IL-22 by IL-22RA2 provide proof of conceptthat other IL-22 antagonists, such as IL-22RA or antibodies thereto, canalso be used to ameliorate symptoms in the LPS-induced model and alterthe course of disease. The model showed induction of IL-22 by LPSinjection and the potential treatment of disease by IL-22RA2polypeptides. Since LPS induces the production of pro-inflammatoryIL-22, SAA or other pro-inflammatory factors possibly contributing tothe pathology of endotoxemia, the neutralization of IL-22 activity, SAAor other pro-inflammatory factors by an antagonist IL-22RA2poloyepeptide can be used to reduce the symptoms of endotoxemia, such asseen in endotoxic shock. Other potential therapeutics include IL-22RApolypeptides, anti-IL-22RA antibodies, or anti IL-22 antibodies orbinding partners, and the like.

3 Inflammatory Bowel Disease. IBD

In the United States approximately 500,000 people suffer fromInflammatory Bowel Disease (IBD) which can affect either colon andrectum (Ulcerative colitis) or both, small and large intestine (Crohn'sDisease). The pathogenesis of these diseases is unclear, but theyinvolve chronic inflammation of the affected tissues. IL-22RApolypeptides, anti-IL-22RA antibodies, or anti IL-22 antibodies orbinding partners, could serve as a valuable therapeutic to reduceinflammation and pathological effects in IBD and related diseases.

Ulcerative colitis (UC) is an inflammatory disease of the largeintestine, commonly called the colon, characterized by inflammation andulceration of the mucosa or innermost lining of the colon. Thisinflammation causes the colon to empty frequently, resulting indiarrhea. Symptoms include loosening of the stool and associatedabdominal cramping, fever and weight loss. Although the exact cause ofUC is unknown, recent research suggests that the body's natural defensesare operating against proteins in the body which the body thinks areforeign (an “autoimmune reaction”). Perhaps because they resemblebacterial proteins in the gut, these proteins may either instigate orstimulate the inflammatory process that begins to destroy the lining ofthe colon. As the lining of the colon is destroyed, ulcers formreleasing mucus, pus and blood. The disease usually begins in the rectalarea and may eventually extend through the entire large bowel. Repeatedepisodes of inflammation lead to thickening of the wall of the intestineand rectum with scar tissue. Death of colon tissue or sepsis may occurwith severe disease. The symptoms of ulcerative colitis vary in severityand their onset may be gradual or sudden. Attacks may be provoked bymany factors, including respiratory infections or stress.

Although there is currently no cure for UC available, treatments arefocused on suppressing the abnormal inflammatory process in the colonlining. Treatments including corticosteroids immunosuppressives (eg.azathioprine, mercaptopurine, and methotrexate) and aminosalicytates areavailable to treat the disease. However, the long-term use ofimmunosuppressives such as corticosteroids and azathioprine can resultin serious side effects including thinning of bones, cataracts,infection, and liver and bone marrow effects. In the patients in whomcurrent therapies are not successful, surgery is an option. The surgeryinvolves the removal of the entire colon and the rectum.

There are several animal models that can partially mimic chroniculcerative colitis. The most widely used model is the2,4,6-trinitrobenesulfonic acid/ethanol (TNBS) induced colitis model,which induces chronic inflammation and ulceration in the colon. WhenTNBS is introduced into the colon of susceptible mice via intra-rectalinstillation, it induces T-cell mediated immune response in the colonicmucosa, in this case leading to a massive mucosal inflammationcharacterized by the dense infiltration of T-cells and macrophagesthroughout the entire wall of the large bowel. Moreover, thishistopathologic picture is accompanies by the clinical picture ofprogressive weight loss (wasting), bloody diarrhea, rectal prolapse, andlarge bowel wall thickening (Neurath et al. Intern. Rev. Immunol.19:51-62, 2000).

Another colitis model uses dextran sulfate sodium (DSS), which inducesan acute colitis manifested by bloody diarrhea, weight loss, shorteningof the colon and mucosal ulceration with neutrophil infiltration.DSS-induced colitis is characterized histologically by infiltration ofinflammatory cells into the lamina propria, with lymphoid hyperplasia,focal crypt damage, and epithelial ulceration. These changes are thoughtto develop due to a toxic effect of DSS on the epithelium and byphagocytosis of lamina propria cells and production of TNF-alpha andIFN-gamma. Despite its common use, several issues regarding themechanisms of DSS about the relevance to the human disease remainunresolved. DSS is regarded as a T cell-independent model because it isobserved in T cell-deficient animals such as SCID mice.

The administration of soluble IL-22RA2 comprising polypeptides, such aszcytor16-Fc4 or other IL-22RA soluble and fusion proteins to these TNBSor DSS models can be used to evaluate the use of IL-22RA to amelioratesymptoms and alter the course of gastrointestinal disease. Moreover, theresults showing inhibition of IL-22 by IL-22RA2 provide proof of conceptthat other IL-22 antagonists, such as IL-22RA or antibodies thereto, canalso be used to ameliorate symptoms in the colitis/IBD models and alterthe course of disease. We observed the increased expression of IL-22 incolon tissues of DSS-mice by RT-PCR, and the synergistic activity ofIL-22 with IL-1beta on intestinal cell lines. It indicates IL-22 mayplay a role in the inflammatory response in colitis, and theneutralization of IL-22 activity by administrating IL-22RA2 polypeptidesis a potential therapeutic approach for IBD. Other potentialtherapeutics include IL-22RA polypeptides, anti-IL-22RA antibodies, oranti IL-22 antibodies or binding partners, and the like.

4. Psoriasis

Psoriasis is a chronic skin condition that affects more than sevenmillion Americans. Psoriasis occurs when new skin cells grow abnormally,resulting in inflamed, swollen, and scaly patches of skin where the oldskin has not shed quickly enough. Plaque psoriasis, the most commonform, is characterized by inflamed patches of skin (“lesions”) toppedwith silvery white scales. Psoriasis may be limited to a few plaques orinvolve moderate to extensive areas of skin, appearing most commonly onthe scalp, knees, elbows and trunk. Although it is highly visible,psoriasis is not a contagious disease. The pathogenesis of the diseasesinvolves chronic inflammation of the affected tissues. IL-22RApolypeptides, anti-IL-22RA antibodies, or anti IL-22 and anti IL-20antibodies or binding partners, could serve as a valuable therapeutic toreduce inflammation and pathological effects in psoriasis, otherinflammatory skin diseases, skin and mucosal allergies, and relateddiseases.

Psoriasis is a T-cell mediated inflammatory disorder of the skin thatcan cause considerable discomfort. It is a disease for which there is nocure and affects people of all ages. Psoriasis affects approximately twopercent of the populations of European and North America. Althoughindividuals with mild psoriasis can often control their disease withtopical agents, more than one million patients worldwide requireultraviolet or systemic immunosuppressive therapy. Unfortunately, theinconvenience and risks of ultraviolet radiation and the toxicities ofmany therapies limit their long-term use. Moreover, patients usuallyhave recurrence of psoriasis, and in some cases rebound, shortly afterstopping immunosuppressive therapy.

IL-20 is a novel IL-10 homologue that was shown to cause neonatallethality with skin abnormalities including aberrant epidermaldifferentiation in IL-20 transgenic mice (Blumberg H et al., Cell104:9-19, 2001) IL-20 receptor is dramatically upregulated in psoriaticskin. Since IL-22 shares a receptor subunit (zcytor11) with IL-20receptor, and IL-22 transgenic mice display a similar phenotype, it ispossible that IL-22 is also involved in the inflammatory skin diseasessuch as psoriasis. The administration of IL-22RA polypeptide or ananti-IL-22RA antibody antagonist, either subcutaneous or topically, maypotential reduce the inflammation and symptom. Other potentialtherapeutics include IL-22RA polypeptides, soluble zcytor11/CRF2-4receptor polypeptides, or anti IL-22 antibodies or binding partners, andthe like.

Moreover, over expression of IL-22 and IL-20 was shown in humanpsoriatic lesions, suggesting that IL-22, like IL-20 is also involved inhuman psoriasis. Moreover, as described herein, over expression of IL-20or IL-22 in transgenic mice showed epidermal thickening and immune cellinvolvement indicative of a psoriatic phenotype; and in additioninjection of IL-22 into normal mice showed epidermal thickening andimmune cell involvement indicative of a psoriatic phenotype which wasablated by the soluble receptor antagonist IL-22RA2 (zcytor16; WIPOPublication No. WO 01/40467). Such in vivo data further suggests thatthe pro-inflammatory IL-22 is involved in psoriasis. As such,antagonists to IL-22 and IL-20 activity, such as IL-22RA solublereceptors and antibodies thereto including the anti-human-IL-22RAmonoclonal and neutralizing antibodies of the present invention, areuseful in therapeutic treatment of inflammatory diseases, particularlyas antagonists to both IL-22 and IL-20 singly or together in thetreatment of psoriasis. Moreover, antagonists to IL-22 activity, such asIL-22RA soluble receptors and antibodies thereto including theanti-human-IL-22RA monoclonal and neutralizing antibodies of the presentinvention, are useful in therapeutic treatment of other inflammatorydiseases for example as agents that bind to, block, inhibit, reduce,antagonize or neutralize IL-22 and IL-20 in the treatment of atopicdermatitis, IBD, colitis, Endotoxemia, arthritis, rheumatoid arthritis,and psoriatic arthritis adult respiratory disease (ARD), septic shock,multiple organ failure, inflammatory lung injury such as asthma orbronchitis, bacterial pneumonia, psoriasis, eczema, atopic and contactdermatitis, and inflammatory bowel disease such as ulcerative colitisand Crohn's disease.

Moreover, anti-IL-22RA antibodies and IL-22RA soluble receptors of thepresent invention can be used in the prevention and therapy againstweight loss associated with a number of inflammatory diseases describedherein, as well as for cancer (e.g., chemotherapy and cachexia), andinfectious diseases. For example, severe weight loss is a key markerassociated with models for septicemia, MS, RA, and tumor models. Inaddition, weight loss is a key parameter for many human diseasesincluding cancer, infectious disease and inflammatory disease. Weightloss was shown in mice injected with IL-22Adenovirus described herein.Anti-IL-22 antibodies and IL-22 antagonists such as the soluble IL-22RAreceptors and antibodies thereto of the present invention, as well aszcytor16 (IL-22RA2) receptors, can be tested for their ability toprevent and treat weight loss in mice injected with IL-22 andenoviresdescribed herein. Methods of determining a prophylactic or therapeuticregimen for such IL-22 antagonists is known in the art and can bedetermined using the methods described herein.

IL-22RA soluble receptor polypeptides and antibodies thereto may also beused within diagnostic systems for the detection of circulating levelsof IL-22 or IL-20 ligand, and in the detection of IL-22 associated withacute phase inflammatory response. Within a related embodiment,antibodies or other agents that specifically bind to IL-22RA solublereceptors of the present invention can be used to detect circulatingreceptor polypeptides; conversely, IL-22RA soluble receptors themselvescan be used to detect circulating or locally-acting IL-22 or IL-20polypeptides. Elevated or depressed levels of ligand or receptorpolypeptides may be indicative of pathological conditions, includinginflammation or cancer. IL-22 is known to induce associated acute phaseinflammatory response. Moreover, detection of acute phase proteins ormolecules such as IL-20 or IL-22 can be indicative of a chronicinflammatory condition in certain disease states (e.g., psoriasis,rheumatoid arthritis, colitis, IBD). Detection of such conditions servesto aid in disease diagnosis as well as help a physician in choosingproper therapy.

In utero administration of neutralizing anti-IL-22 or IL-20 antibodiescan be used to show efficacy in vivo in disease models by reducing oreliminating the skin phenotype found IL-22 transgenic pups which overexpress IL-22, or IL-20 transgenic pups which over express IL-20. Thereare precedents in the art for in utero treatment with neutralizingmonoclonal antibodies (mAbs). In one case, the development of the B-1subset of B cells was dramatically affected by treating pregnant femalemice with a mAb specific for the B cell-specific molecule, CD19 (e.g.,Krop I. Et al., Eur. J. Immunol. 26(1):238-42, 1996). Krop et al.injected timed pregnant mice intraperitoneally with 500 ug of ratanti-mouse CD19 mAb (or a rat isotype-matched control Ab) in PBSbeginning on day 9 of gestation, with subsequent injections every otherday until birth. Pups were also injected once with 500 ug of theseantibodies at 10 days of age. In another case, Tanaka et al., found thatin utero treatment with monoclonal antibody to IL-2 receptor beta-chaincompletely abrogates development of Thy-1+ dendritic epidermal cells.The two distinct subunits of the IL-2 receptor, i.e. the alpha-chain(IL-2R alpha) and the beta-chain (IL-2R beta), are expressed in analmost mutually exclusive fashion throughout fetal thymus ontogeny.Blocking IL-2R beta, a signal transducing component of IL-2R, byadministering a neutralizing mAb to IL-2R beta, resulted in the completeand selective disappearance of Thy-1+ skin dendritic epidermal cells.Development of any other T cell subsets was uncompromised. Thisindicated that IL-2 plays a crucial role in the development of fetal Vgamma 5+ cells and their descendants (see, Tanaka, T. et al., IntImmunol. 4(4):487-9, 1992). In addition, Schattemann G C et al., showedthat PDGF-A is required for normal murine cardiovascular developmentusing an in utero system. Several lines of evidence suggest thatplatelet-derived growth factor A chain (PDGF-A) is required for normalembryonic cardiovascular development. Introduction of anti-PDGF-Aneutralizing antibodies into mouse deciduas in utero resulted in theselective disruption of PDGF-A ligand-receptor interactions in vivo fora period of 18-24 hr and allowed assessment of whether PDGF-A isrequired for cardiovascular development and when it is required (see,Schattemann G C et al., Dev. Biol. 176(1):133-42, 1996). These results,as well as others described in the art, provide evidence thatneutralizing mAbs can elicit strong effects in utero. Similarly, datashowing the efficacy of neutralizing IL-20 or IL-22 with monoclonalantibodies in vivo in disease models to reduce or eliminate the skinphenotype found in IL-20 and IL-22 transgenic pups which over expressIL-20 and IL-22 respectively can be shown. These transgenic mice areborn with a “shiny” skin appearance, due at least in part to athickening of the epidermis as described herein. The IL-20 TG pupsexpressing fairly low levels of the transgenic cytokine can recover anddo survive to breed, but the IL-22 TG mice die shortly after birth,generally before 5 days of age.

For example, neutralizing antibodies to IL-20 include antibodies, suchas neutralizing monoclonal antibodies that can bind IL-20 antigenicepitopes and neutralize IL-20 activity. Accordingly, antigenicepitope-bearing peptides and polypeptides of IL-20 are useful to raiseantibodies that bind with the IL-20 polypeptides described herein, aswell as to identify and screen anti-IL-20 monoclonal antibodies that areneutralizing, and that may bind, block, inhibit, reduce, antagonize orneutralize the activity of IL-20. Such neutralizing monoclonalantibodies of the present invention can bind to an IL-20 antigenicepitope. Such epitopes within SEQ ID NO:8 as predicted by a Jameson-Wolfplot, e.g., using DNASTAR Protean program (DNASTAR, Inc., Madison, Wis.)serve as preferred antigenic epitopes, and can be determined by one ofskill in the art. Such antigenic epitopes include: amino acid residues42 (Ile) to 102 (Asp) of SEQ ID NO:8; amino acid residues 42 (Ile) to 60(Ile) of SEQ ID NO:8; amino acid residues 42 (Ile) to 69 (Glu) of SEQ IDNO:8; amino acid residues 42 (Ile) to 81 (Cys) of SEQ ID NO:8; aminoacid residues 42 (Ile) to 96 (Lys) of SEQ ID NO:8; amino acid residues42 (Ile) to 102 (Asp) of SEQ ID NO:8; amino acid residues 60 (Ile) to 69(Glu) of SEQ ID NO:8; amino acid residues 60 (Ile) to 81 (Cys) of SEQ IDNO:8; amino acid residues 60 (Ile) to 96 (Lys) of SEQ ID NO:8; aminoacid residues 60 (Ile) to 102 (Asp) of SEQ ID NO:8; amino acid residues69 (Glu) to 81 (Cys) of SEQ ID NO:8; amino acid residues 69 (Glu) to 96(Lys) of SEQ ID NO:8; amino acid residues 69 (Glu) to 102 (Asp) of SEQID NO:8; amino acid residues 81 (Cys) to 96 (Lys) of SEQ ID NO:8; aminoacid residues 81 (Cys) to 102 (Asp) of SEQ ID NO:8; and amino acidresidues 96 (Lys) to 102 (Asp) of SEQ ID NO:8.

In addition to other disease models described herein, the activity ofanti-IL-22RA antibodies on inflammatory tissue derived from humanpsoriatic lesions can be measured in vivo using a severe combined immunedeficient (SCID) mouse model. Several mouse models have been developedin which human cells are implanted into immunodeficient mice(collectively referred to as xenograft models); see, for example, CattanA R, Douglas E, Leuk. Res. 18:513-22, 1994 and Flavell, D J,Hematological Oncology 14:67-82, 1996. As an in vivo xenograft model forpsoriasis, human psoriatic skin tissue is implanted into the SCID mousemodel, and challenged with an appropriate antagonist. Moreover, otherpsoriasis animal models in ther art may be used to evaluate IL-20 andIL-22 antagonists, such as human psoriatic skin grafts implanted intoAGR129 mouse model, and challenged with an appropriate antagonist (e.g.,see, Boyman, O. et al., J. Exp. Med. Online publication #20031482, 2004,incorporated herein by reference). Anti-IL-22RA antibodies that bind,block, inhibit, reduce, antagonize or neutralize the activity of IL-22or both IL-20 and IL-22 are preferred antagonists, however, anti-IL-20and anti-IL-22 antibodies (alone or in combination), soluble IL-22RA, aswell as other IL-20 and IL-22 antagonists can be used in this model.Similarly, tissues or cells derived from human colitis, IBD, arthritis,or other inflammatory lestions can be used in the SCID model to assessthe anti-inflammatory properties of the IL-20 and IL-22 antagonistsdescribed herein.

Therapies designed to abolish, retard, or reduce inflammation usinganti-IL-22RA antibodies or its derivatives, agonists, conjugates orvariants can be tested by administration of anti-IL-22RA antibodies orsoluble IL-22RA compounds to SCID mice bearing human inflammatory tissue(e.g., psoriatic lesions and the like), or other models describedherein. Efficacy of treatment is measured and statistically evaluated asincreased anti-inflammatory effect within the treated population overtime using methods well known in the art. Some exemplary methodsinclude, but are not limited to measuring for example, in a psoriasismodel, epidermal thickness, the number of inflammatory cells in theupper dermis, and the grades of parakeratosis. Such methods are known inthe art and described herein. For example, see Zeigler, M. et al. LabInvest 81:1253, 2001; Zollner, T. M. et al. J. Clin. Invest. 109:671,2002; Yamanaka, N. et al. Microbiol. Immunol. 45:507, 2001;Raychaudhuri, S. P. et al. Br. J. Dermatol. 144:931, 2001; Boehncke, W.H et al. Arch. Dermatol. Res. 291:104, 1999; Boehncke, W. H et al. J.Invest. Dermatol. 116:596, 2001; Nickoloff, B. J. et al. Am. J. Pathol.146:580, 1995; Boehncke, W. H et al. J. Cutan. Pathol. 24:1, 1997;Sugai, J., M. et al. J. Dermatol. Sci. 17:85, 1998; and Villadsen L. S.et al. J. Clin. Invest. 112:1571, 2003. Inflammation may also bemonitored over time using well-known methods such as flow cytometry (orPCR) to quantitate the number of inflammatory or lesional cells presentin a sample, score (weight loss, diarrhea, rectal bleeding, colonlength) for IBD, paw disease score and inflammation score for CIA RAmodel. For example, therapeutic strategies appropriate for testing insuch a model include direct treatment using anti-IL-22RA antibodies,other IL-20 and IL-22 antagonists (singly or together), or relatedconjugates or antagonists based on the disrupting interaction ofanti-IL-22RA antibodies with its ligands IL-20 and IL-22, or forcell-based therapies utilizing anti-IL-22RA antibodies or itsderivatives, agonists, conjugates or variants.

Moreover, Psoriasis is a chronic inflammatory skin disease that isassociated with hyperplastic epidermal keratinocytes and infiltratingmononuclear cells, including CD4+ memory T cells, neutrophils andmacrophages (Christophers, Int. Arch. Allergy Immunol., 110:199, 1996).It is currently believed that environmental antigens play a significantrole in initiating and contributing to the pathology of the disease.However, it is the loss of tolerance to self-antigens that is thought tomediate the pathology of psoriasis. Dendritic cells and CD4⁺ T cells arethought to play an important role in antigen presentation andrecognition that mediate the immune response leading to the pathology.We have recently developed a model of psoriasis based on the CD4+CD45RBtransfer model (Davenport et al., Internat. Immunopharmacol.,2:653-672). Anti-IL20, anti-IL22 or antibodies to IL20R and/or IL22R,such as anti-IL-22RA antibodies of the present invention, or solubleIL-22RA, are administered to the mice. Inhibition of disease scores(skin lesions, inflammatory cytokines) indicates the effectiveness ofIL-20 and IL-22 antagonists in psoriasis, e.g., anti-IL-22RA antibodiesor IL-22RA soluble receptors, or other antagonists such as antibodiesagainst IL20 and/or IL-22 or their receptors.

5. Atopic Dermatitis.

Both IL-20 and IL-22 are upregulated in human atopic dermatitis (AD)patient samples. AD is a common chronic inflammatory disease that ischaracterized by hyperactivated cytokines of the helper T cell subset 2(Th2). Although the exact etiology of AD is unknown, multiple factorshave been implicated, including hyperactive Th2 immune responses,autoimmunity, infection, allergens, and genetic predisposition. Keyfeatures of the disease include xerosis (dryness of the skin), pruritus(itchiness of the skin), conjunctivitis, inflammatory skin lesions,Staphylococcus aureus infection, elevated blood eosinophilia, elevationof serum IgE and IgG1, and chronic dermatitis with T cell, mast cell,macrophage and eosinophil infiltration. Colonization or infection withS. aureus has been recognized to exacerbate AD and perpetuate chronicityof this skin disease.

AD is often found in patients with asthma and allergic rhinitis, and isfrequently the initial manifestation of allergic disease. About 20% ofthe population in Western countries suffer from these allergic diseases,and the incidence of AD in developed countries is rising for unknownreasons. AD typically begins in childhood and can often persist throughadolescence into adulthood. Current treatments for AD include topicalcorticosteroids, oral cyclosporin A, non-corticosteroidimmunosuppressants such as tacrolimus (FK506 in ointment form), andinterferon-gamma. Despite the variety of treatments for AD, manypatients' symptoms do not improve, or they have adverse reactions tomedications, requiring the search for other, more effective therapeuticagents. The soluble IL-22RA polypeptides and anti-IL-22RA antibodies ofthe present invention, including the neutralizing anti-human IL-22RAantibodies of the present invention, can be used to neutralize IL-22 andIL-20 in the treatment of specific human diseases such as atopticdermatitis, inflammatory skin conditions, and other inflammatoryconditions disclosed herein.

For pharmaceutical use, the soluble IL-22RA or anti-IL-22RA antibodiesof the present invention are formulated for parenteral, particularlyintravenous or subcutaneous, delivery according to conventional methods.Intravenous administration will be by bolus injection, controlledrelease, e.g, using mini-pumps or other appropriate technology, or byinfusion over a typical period of one to several hours. In general,pharmaceutical formulations will include a hematopoietic protein incombination with a pharmaceutically acceptable vehicle, such as saline,buffered saline, 5% dextrose in water or the like. Formulations mayfurther include one or more excipients, preservatives, solubilizers,buffering agents, albumin to provent protein loss on vial surfaces, etc.When utilizing such a combination therapy, the cytokines may be combinedin a single formulation or may be administered in separate formulations.Methods of formulation are well known in the art and are disclosed, forexample, in Remington's Pharmaceutical Sciences, Gennaro, ed., MackPublishing Co., Easton Pa., 1990, which is incorporated herein byreference. Therapeutic doses will generally be in the range of 0.1 to100 mg/kg of patient weight per day, preferably 0.5-20 mg/kg per day,with the exact dose determined by the clinician according to acceptedstandards, taking into account the nature and severity of the conditionto be treated, patient traits, etc. Determination of dose is within thelevel of ordinary skill in the art. The proteins will commonly beadministered over a period of up to 28 days following chemotherapy orbone-marrow transplant or until a platelet count of >20,000/mm³,preferably >50,000/mm³, is achieved. More commonly, the proteins will beadministered over one week or less, often over a period of one to threedays. In general, a therapeutically effective amount of soluble IL-22RAor anti-IL-22RA antibodies of the present invention is an amountsufficient to produce a clinically significant increase in theproliferation and/or differentiation of lymphoid or myeloid progenitorcells, which will be manifested as an increase in circulating levels ofmature cells (e.g. platelets or neutrophils). Treatment of plateletdisorders will thus be continued until a platelet count of at least20,000/mm³, preferably 50,000/mm³, is reached. The soluble IL-22RA oranti-IL-22RA antibodies of the present invention can also beadministered in combination with other cytokines such as IL-3, -6 and-11; stem cell factor; erythropoietin; G-CSF and GM-CSF. Within regimensof combination therapy, daily doses of other cytokines will in generalbe: EPO, 150 U/kg; GM-CSF, 5-15 lg/kg; IL-3, 1-5 lg/kg; and G-CSF, 1-25lg/kg. Combination therapy with EPO, for example, is indicated in anemicpatients with low EPO levels.

Generally, the dosage of administered soluble IL-22RA (or IL-22RA analogor fusion protein) or anti-IL-22RA antibodies will vary depending uponsuch factors as the patient's age, weight, height, sex, general medicalcondition and previous medical history. Typically, it is desirable toprovide the recipient with a dosage of soluble IL-22RA or anti-IL-22RAantibodies which is in the range of from about 1 pg/kg to 10 mg/kg(amount of agent/body weight of patient), although a lower or higherdosage also may be administered as circumstances dictate.

Administration of soluble IL-22RA or anti-IL-22RA antibodies to asubject can be intravenous, intraarterial, intraperitoneal,intramuscular, subcutaneous, intrapleural, intrathecal, by perfusionthrough a regional catheter, or by direct intralesional injection. Whenadministering therapeutic proteins by injection, the administration maybe by continuous infusion or by single or multiple boluses.

Additional routes of administration include oral, mucosal-membrane,pulmonary, and transcutaneous. Oral delivery is suitable for polyestermicrospheres, zein microspheres, proteinoid microspheres,polycyanoacrylate microspheres, and lipid-based systems (see, forexample, DiBase and Morrel, “Oral Delivery of MicroencapsulatedProteins,” in Protein Delivery: Physical Systems, Sanders and Hendren(eds.), pages 255-288 (Plenum Press 1997)). The feasibility of anintranasal delivery is exemplified by such a mode of insulinadministration (see, for example, Hinchcliffe and Illum, Adv. DrugDeliv. Rev. 35:199 (1999)). Dry or liquid particles comprising IL-22RAcan be prepared and inhaled with the aid of dry-powder dispersers,liquid aerosol generators, or nebulizers (e.g., Pettit and Gombotz,TIBTECH 16:343 (1998); Patton et al., Adv. Drug Deliv. Rev. 35:235(1999)). This approach is illustrated by the AERX diabetes managementsystem, which is a hand-held electronic inhaler that deliversaerosolized insulin into the lungs. Studies have shown that proteins aslarge as 48,000 kDa have been delivered across skin at therapeuticconcentrations with the aid of low-frequency ultrasound, whichillustrates the feasibility of trascutaneous administration (Mitragotriet al., Science 269:850 (1995)). Transdermal delivery usingelectroporation provides another means to administer a molecule havingIL-22RA binding activity (Potts et al., Pharm. Biotechnol. 10:213(1997)).

A pharmaceutical composition comprising a soluble IL-22RA oranti-IL-22RA antibody can be formulated according to known methods toprepare pharmaceutically useful compositions, whereby the therapeuticproteins are combined in a mixture with a pharmaceutically acceptablecarrier. A composition is said to be a “pharmaceutically acceptablecarrier” if its administration can be tolerated by a recipient patient.Sterile phosphate-buffered saline is one example of a pharmaceuticallyacceptable carrier. Other suitable carriers are well-known to those inthe art. See, for example, Gennaro (ed.), Remington's PharmaceuticalSciences, 19th Edition (Mack Publishing Company 1995).

For purposes of therapy, soluble IL-22RA or anti-IL-22RA antibodymolecules and a pharmaceutically acceptable carrier are administered toa patient in a therapeutically effective amount. A combination of atherapeutic molecule of the present invention and a pharmaceuticallyacceptable carrier is said to be administered in a “therapeuticallyeffective amount” if the amount administered is physiologicallysignificant. An agent is physiologically significant if its presenceresults in a detectable change in the physiology of a recipient patient.For example, an agent used to treat inflammation is physiologicallysignificant if its presence alleviates the inflammatory response.

A pharmaceutical composition comprising IL-22RA (or IL-22RA analog orfusion protein) or neutralizing anti-IL-22RA antibody can be furnishedin liquid form, in an aerosol, or in solid form. Liquid forms, areillustrated by injectable solutions and oral suspensions. Exemplarysolid forms include capsules, tablets, and controlled-release forms. Thelatter form is illustrated by miniosmotic pumps and implants (Bremer etal., Pharm. Biotechnol. 10:239 (1997); Ranade, “Implants in DrugDelivery,” in Drug Delivery Systems, Ranade and Hollinger (eds.), pages95-123 (CRC Press 1995); Bremer et al., “Protein Delivery with InfusionPumps,” in Protein Delivery: Physical Systems, Sanders and Hendren(eds.), pages 239-254 (Plenum Press 1997); Yewey et al., “Delivery ofProteins from a Controlled Release Injectable Implant,” in ProteinDelivery: Physical Systems, Sanders and Hendren (eds.), pages 93-117(Plenum Press 1997)).

Liposomes provide one means to deliver therapeutic polypeptides to asubject intravenously, intraperitoneally, intrathecally,intramuscularly, subcutaneously, or via oral administration, inhalation,or intranasal administration. Liposomes are microscopic vesicles thatconsist of one or more lipid bilayers surrounding aqueous compartments(see, generally, Bakker-Woudenberg et al., Eur. J. Clin. Microbiol.Infect. Dis. 12 (Suppl. 1):S61 (1993), Kim, Drugs 46:618 (1993), andRanade, “Site-Specific Drug Delivery Using Liposomes as Carriers,” inDrug Delivery Systems, Ranade and Hollinger (eds.), pages 3-24 (CRCPress 1995)). Liposomes are similar in composition to cellular membranesand as a result, liposomes can be administered safely and arebiodegradable. Depending on the method of preparation, liposomes may beunilamellar or multilamellar, and liposomes can vary in size withdiameters ranging from 0.02 μm to greater than 10 μm. A variety ofagents can be encapsulated in liposomes: hydrophobic agents partition inthe bilayers and hydrophilic agents partition within the inner aqueousspace(s) (see, for example, Machy et al., Liposomes In Cell Biology AndPharmacology (John Libbey 1987), and Ostro et al., American J. Hosp.Pharm. 46:1576 (1989)). Moreover, it is possible to control thetherapeutic availability of the encapsulated agent by varying liposomesize, the number of bilayers, lipid composition, as well as the chargeand surface characteristics of the liposomes.

Liposomes can adsorb to virtually any type of cell and then slowlyrelease the encapsulated agent. Alternatively, an absorbed liposome maybe endocytosed by cells that are phagocytic. Endocytosis is followed byintralysosomal degradation of liposomal lipids and release of theencapsulated agents (Scherphof et al., Ann. N.Y. Acad. Sci. 446:368(1985)). After intravenous administration, small liposomes (0.1 to 1.0μm) are typically taken up by cells of the reticuloendothelial system,located principally in the liver and spleen, whereas liposomes largerthan 3.0 μm are deposited in the lung. This preferential uptake ofsmaller liposomes by the cells of the reticuloendothelial system hasbeen used to deliver chemotherapeutic agents to macrophages and totumors of the liver.

The reticuloendothelial system can be circumvented by several methodsincluding saturation with large doses of liposome particles, orselective macrophage inactivation by pharmacological means (Claassen etal., Biochim. Biophys. Acta 802:428 (1984)). In addition, incorporationof glycolipid- or polyethelene glycol-derivatized phospholipids intoliposome membranes has been shown to result in a significantly reduceduptake by the reticuloendothelial system (Allen et al., Biochim.Biophys. Acta 1068:133 (1991); Allen et al., Biochim. Biophys. Acta1150:9 (1993)).

Liposomes can also be prepared to target particular cells or organs byvarying phospholipid composition or by inserting receptors or ligandsinto the liposomes. For example, liposomes, prepared with a high contentof a nonionic surfactant, have been used to target the liver (Hayakawaet al., Japanese Patent 04-244,018; Kato et al., Biol. Pharm. Bull.116:960 (1993)). These formulations were prepared by mixing soybeanphospatidylcholine, α-tocopherol, and ethoxylated hydrogenated castoroil (HCO-60) in methanol, concentrating the mixture under vacuum, andthen reconstituting the mixture with water. A liposomal formulation ofdipalmitoylphosphatidylcholine (DPPC) with a soybean-derivedsterylglucoside mixture (SG) and cholesterol (Ch) has also been shown totarget the liver (Shimizu et al., Biol. Pharm. Bull. 20:881 (1997)).

Alternatively, various targeting ligands can be bound to the surface ofthe liposome, such as antibodies, antibody fragments, carbohydrates,vitamins, and transport proteins. For example, liposomes can be modifiedwith branched type galactosyllipid derivatives to targetasialoglycoprotein (galactose) receptors, which are exclusivelyexpressed on the surface of liver cells (Kato and Sugiyama, Crit. Rev.Ther. Drug Carrier Syst. 14:287 (1997); Murahashi et al., Biol. Pharm.Bull. 20:259 (1997)). Similarly, Wu et al., Hepatology 27:772 (1998),have shown that labeling liposomes with asialofetuin led to a shortenedliposome plasma half-life and greatly enhanced uptake ofasialofetuin-labeled liposome by hepatocytes. On the other hand, hepaticaccumulation of liposomes comprising branched type galactosyllipidderivatives can be inhibited by preinjection of asialofetuin (Murahashiet al., Biol. Pharm. Bull. 20:259 (1997)). Polyaconitylated human serumalbumin liposomes provide another approach for targeting liposomes toliver cells (Kamps et al., Proc. Nat'l Acad. Sci. USA 94:11681 (1997)).Moreover, Geho, et al. U.S. Pat. No. 4,603,044, describe ahepatocyte-directed liposome vesicle delivery system, which hasspecificity for hepatobiliary receptors associated with the specializedmetabolic cells of the liver.

In a more general approach to tissue targeting, target cells areprelabeled with biotinylated antibodies specific for a ligand expressedby the target cell (Harasym et al., Adv. Drug Deliv. Rev. 32:99 (1998)).After plasma elimination of free antibody, streptavidin-conjugatedliposomes are administered. In another approach, targeting antibodiesare directly attached to liposomes (Harasym et al., Adv. Drug Deliv.Rev. 32:99 (1998)).

Polypeptides and antibodies can be encapsulated within liposomes usingstandard techniques of protein microencapsulation (see, for example,Anderson et al., Infect. Immun. 31:1099 (1981), Anderson et al., CancerRes. 50:1853 (1990), and Cohen et al., Biochim. Biophys. Acta 1063:95(1991), Alving et al. “Preparation and Use of Liposomes in ImmunologicalStudies,” in Liposome Technology, 2nd Edition, Vol. III, Gregoriadis(ed.), page 317 (CRC Press 1993), Wassef et al., Meth. Enzymol. 149:124(1987)). As noted above, therapeutically useful liposomes may contain avariety of components. For example, liposomes may comprise lipidderivatives of poly(ethylene glycol) (Allen et al., Biochim. Biophys.Acta 1150:9 (1993)).

Degradable polymer microspheres have been designed to maintain highsystemic levels of therapeutic proteins. Microspheres are prepared fromdegradable polymers such as poly(lactide-co-glycolide) (PLG),polyanhydrides, poly (ortho esters), nonbiodegradable ethylvinyl acetatepolymers, in which proteins are entrapped in the polymer (Gombotz andPettit, Bioconjugate Chem. 6:332 (1995); Ranade, “Role of Polymers inDrug Delivery,” in Drug Delivery Systems, Ranade and Hollinger (eds.),pages 51-93 (CRC Press 1995); Roskos and Maskiewicz, “DegradableControlled Release Systems Useful for Protein Delivery,” in ProteinDelivery: Physical Systems, Sanders and Hendren (eds.), pages 45-92(Plenum Press 1997); Bartus et al., Science 281:1161 (1998); Putney andBurke, Nature Biotechnology 16:153 (1998); Putney, Curr. Opin. Chem.Biol. 2:548 (1998)). Polyethylene glycol (PEG)-coated nanospheres canalso provide carriers for intravenous administration of therapeuticproteins (see, for example, Gref et al., Pharm. Biotechnol. 10:167(1997)).

The present invention also contemplates chemically modified polypeptideshaving binding IL-22RA activity such as IL-22RA monomeric, homodimeric,heterodimeric or multimeric soluble receptors, and IL-22RA antagonists,for example anti-IL-22RA antibodies or binding polypeptides, orneutralizing anti-IL-22RA antibodies, which a polypeptide is linked witha polymer, as discussed above.

Other dosage forms can be devised by those skilled in the art, as shown,for example, by Ansel and Popovich, Pharmaceutical Dosage Forms and DrugDelivery Systems, 5^(th) Edition (Lea & Febiger 1990), Gennaro (ed.),Remington's Pharmaceutical Sciences, 19^(th) Edition (Mack PublishingCompany 1995), and by Ranade and Hollinger, Drug Delivery Systems (CRCPress 1996).

As an illustration, pharmaceutical compositions may be supplied as a kitcomprising a container that comprises a polypeptide with a IL-22RAextracellular domain, e.g., IL-22RA monomeric, homodimeric,heterodimeric or multimeric soluble receptors, or a IL-22RA antagonist(e.g., an antibody or antibody fragment that binds a IL-22RApolypeptide, or neutralizing anti-IL-22RA antibody). Therapeuticpolypeptides can be provided in the form of an injectable solution forsingle or multiple doses, or as a sterile powder that will bereconstituted before injection. Alternatively, such a kit can include adry-powder disperser, liquid aerosol generator, or nebulizer foradministration of a therapeutic polypeptide. Such a kit may furthercomprise written information on indications and usage of thepharmaceutical composition. Moreover, such information may include astatement that the IL-22RA composition is contraindicated in patientswith known hypersensitivity to IL-22RA.

A pharmaceutical composition comprising Anti-IL-22RA antibodies orbinding partners (or Anti-IL-22RA antibody fragments, antibody fusions,humanized antibodies and the like), or IL-22RA soluble receptor, can befurnished in liquid form, in an aerosol, or in solid form. Liquid forms,are illustrated by injectable solutions, aerosols, droplets, topologicalsolutions and oral suspensions. Exemplary solid forms include capsules,tablets, and controlled-release forms. The latter form is illustrated byminiosmotic pumps and implants (Bremer et al., Pharm. Biotechnol. 10:239(1997); Ranade, “Implants in Drug Delivery,” in Drug Delivery Systems,Ranade and Hollinger (eds.), pages 95-123 (CRC Press 1995); Bremer etal., “Protein Delivery with Infusion Pumps,” in Protein Delivery:Physical Systems, Sanders and Hendren (eds.), pages 239-254 (PlenumPress 1997); Yewey et al., “Delivery of Proteins from a ControlledRelease Injectable Implant,” in Protein Delivery: Physical Systems,Sanders and Hendren (eds.), pages 93-117 (Plenum Press 1997)). Othersolid forms include creams, pastes, other topological applications, andthe like.

Liposomes provide one means to deliver therapeutic polypeptides to asubject intravenously, intraperitoneally, intrathecally,intramuscularly, subcutaneously, or via oral administration, inhalation,or intranasal administration. Liposomes are microscopic vesicles thatconsist of one or more lipid bilayers surrounding aqueous compartments(see, generally, Bakker-Woudenberg et al., Eur. J. Clin. Microbiol.Infect. Dis. 12 (Suppl. 1):S61 (1993), Kim, Drugs 46:618 (1993), andRanade, “Site-Specific Drug Delivery Using Liposomes as Carriers,” inDrug Delivery Systems, Ranade and Hollinger (eds.), pages 3-24 (CRCPress 1995)). Liposomes are similar in composition to cellular membranesand as a result, liposomes can be administered safely and arebiodegradable. Depending on the method of preparation, liposomes may beunilamellar or multilamellar, and liposomes can vary in size withdiameters ranging from 0.02 μm to greater than 10 μm. A variety ofagents can be encapsulated in liposomes: hydrophobic agents partition inthe bilayers and hydrophilic agents partition within the inner aqueousspace(s) (see, for example, Machy et al., Liposomes In Cell Biology AndPharmacology (John Libbey 1987), and Ostro et al., American J. Hosp.Pharm. 46:1576 (1989)). Moreover, it is possible to control thetherapeutic availability of the encapsulated agent by varying liposomesize, the number of bilayers, lipid composition, as well as the chargeand surface characteristics of the liposomes.

Liposomes can adsorb to virtually any type of cell and then slowlyrelease the encapsulated agent. Alternatively, an absorbed liposome maybe endocytosed by cells that are phagocytic. Endocytosis is followed byintralysosomal degradation of liposomal lipids and release of theencapsulated agents (Scherphof et al., Ann. N.Y. Acad. Sci. 446:368(1985)). After intravenous administration, small liposomes (0.1 to 1.0μm) are typically taken up by cells of the reticuloendothelial system,located principally in the liver and spleen, whereas liposomes largerthan 3.0 μm are deposited in the lung. This preferential uptake ofsmaller liposomes by the cells of the reticuloendothelial system hasbeen used to deliver chemotherapeutic agents to macrophages and totumors of the liver.

The reticuloendothelial system can be circumvented by several methodsincluding saturation with large doses of liposome particles, orselective macrophage inactivation by pharmacological means (Claassen etal., Biochim. Biophys. Acta 802:428 (1984)). In addition, incorporationof glycolipid- or polyethelene glycol-derivatized phospholipids intoliposome membranes has been shown to result in a significantly reduceduptake by the reticuloendothelial system (Allen et al., Biochim.Biophys. Acta 1068:133 (1991); Allen et al., Biochim. Biophys. Acta1150:9 (1993)).

Liposomes can also be prepared to target particular cells or organs byvarying phospholipid composition or by inserting receptors or ligandsinto the liposomes. For example, liposomes, prepared with a high contentof a nonionic surfactant, have been used to target the liver (Hayakawaet al., Japanese Patent 04-244,018; Kato et al., Biol. Pharm. Bull.16:960 (1993)). These formulations were prepared by mixing soybeanphospatidylcholine, α-tocopherol, and ethoxylated hydrogenated castoroil (HCO-60) in methanol, concentrating the mixture under vacuum, andthen reconstituting the mixture with water. A liposomal formulation ofdipalmitoylphosphatidylcholine (DPPC) with a soybean-derivedsterylglucoside mixture (SG) and cholesterol (Ch) has also been shown totarget the liver (Shimizu et al., Biol. Pharm. Bull. 20:881 (1997)).

Alternatively, various targeting ligands can be bound to the surface ofthe liposome, such as antibodies, antibody fragments, carbohydrates,vitamins, and transport proteins. For example, liposomes can be modifiedwith branched type galactosyllipid derivatives to targetasialoglycoprotein (galactose) receptors, which are exclusivelyexpressed on the surface of liver cells (Kato and Sugiyama, Crit. Rev.Ther. Drug Carrier Syst. 14:287 (1997); Murahashi et al., Biol. Pharm.Bull. 20:259 (1997)). Similarly, Wu et al., Hepatology 27:772 (1998),have shown that labeling liposomes with asialofetuin led to a shortenedliposome plasma half-life and greatly enhanced uptake ofasialofetuin-labeled liposome by hepatocytes. On the other hand, hepaticaccumulation of liposomes comprising branched type galactosyllipidderivatives can be inhibited by preinjection of asialofetuin (Murahashiet al., Biol. Pharm. Bull. 20:259 (1997)). Polyaconitylated human serumalbumin liposomes provide another approach for targeting liposomes toliver cells (Kamps et al., Proc. Nat'l Acad. Sci. USA 94:11681 (1997)).Moreover, Geho, et al. U.S. Pat. No. 4,603,044, describe ahepatocyte-directed liposome vesicle delivery system, which hasspecificity for hepatobiliary receptors associated with the specializedmetabolic cells of the liver.

In a more general approach to tissue targeting, target cells areprelabeled with biotinylated antibodies specific for a ligand expressedby the target cell (Harasym et al., Adv. Drug Deliv. Rev. 32:99 (1998)).After plasma elimination of free antibody, streptavidin-conjugatedliposomes are administered. In another approach, targeting antibodiesare directly attached to liposomes (Harasym et al., Adv. Drug Deliv.Rev. 32:99 (1998)).

Anti-IL-22RA neutralizing antibodies and binding partners with IL-22 ORIL-20 binding activity, or IL-22RA soluble receptor, can be encapsulatedwithin liposomes using standard techniques of protein microencapsulation(see, for example, Anderson et al., Infect. Immun. 31:1099 (1981),Anderson et al., Cancer Res. 50:1853 (1990), and Cohen et al., Biochim.Biophys. Acta 1063:95 (1991), Alving et al. “Preparation and Use ofLiposomes in Immunological Studies,” in Liposome Technology, 2ndEdition, Vol. III, Gregoriadis (ed.), page 317 (CRC Press 1993), Wassefet al., Meth. Enzymol. 149:124 (1987)). As noted above, therapeuticallyuseful liposomes may contain a variety of components. For example,liposomes may comprise lipid derivatives of poly(ethylene glycol) (Allenet al., Biochim. Biophys. Acta 1150:9 (1993)).

Degradable polymer microspheres have been designed to maintain highsystemic levels of therapeutic proteins. Microspheres are prepared fromdegradable polymers such as poly(lactide-co-glycolide) (PLG),polyanhydrides, poly (ortho esters), nonbiodegradable ethylvinyl acetatepolymers, in which proteins are entrapped in the polymer (Gombotz andPettit, Bioconjugate Chem. 6:332 (1995); Ranade, “Role of Polymers inDrug Delivery,” in Drug Delivery Systems, Ranade and Hollinger (eds.),pages 51-93 (CRC Press 1995); Roskos and Maskiewicz, “DegradableControlled Release Systems Useful for Protein Delivery,” in ProteinDelivery: Physical Systems, Sanders and Hendren (eds.), pages 45-92(Plenum Press 1997); Bartus et al., Science 281:1161 (1998); Putney andBurke, Nature Biotechnology 16:153 (1998); Putney, Curr. Opin. Chem.Biol. 2:548 (1998)). Polyethylene glycol (PEG)-coated nanospheres canalso provide carriers for intravenous administration of therapeuticproteins (see, for example, Gref et al., Pharm. Biotechnol. 10:167(1997)).

The present invention also contemplates chemically modified Anti-IL-22RAantibody or binding partner, for example anti-Anti-IL-22RA antibodies orIL-22RA soluble receptor, linked with a polymer, as discussed above.

Other dosage forms can be devised by those skilled in the art, as shown,for example, by Ansel and Popovich, Pharmaceutical Dosage Forms and DrugDelivery Systems, 5^(th) Edition (Lea & Febiger 1990), Gennaro (ed.),Remington's Pharmaceutical Sciences, 19^(th) Edition (Mack PublishingCompany 1995), and by Ranade and Hollinger, Drug Delivery Systems (CRCPress 1996).

The present invention contemplates compositions of anti-IL-22antibodies, and methods and therapeutic uses comprising an antibody,peptide or polypeptide described herein. Such compositions can furthercomprise a carrier. The carrier can be a conventional organic orinorganic carrier. Examples of carriers include water, buffer solution,alcohol, propylene glycol, macrogol, sesame oil, corn oil, and the like.

11. Production of Transgenic Mice

Over expression of both IL-20 and IL-22 was shown in human psoriaticlesions, suggesting that both IL-20 and IL-22 are involved in humanpsoriasis. Moreover, as described herein, over expression of IL-20 andIL-22 in transgenic mice showed epidermal thickening and immune cellinvolvement indicative of a psoriatic phenotype; and in additioninjection of IL-22 into normal mice showed epidermal thickening andimmune cell involvement indicative of a psoriatic phenotype which wasablated by the soluble receptor antagonist zcytor16 (IL-22RA2). Such invivo data further suggests that the pro-inflammatory IL-22 is involvedin psoriasis. As such, antagonists to IL-22 activity, such as theanti-human-IL-22RA neutralizing and monoclonal antibodies of the presentinvention, as well as soluble IL-22RA receptors, are useful intherapeutic treatment of inflammatory diseases, particularly asantagonists to IL-22 and IL-20 in the treatment of psoriasis. Moreover,aagents that bind to, block, inhibit, reduce, antagonize or neutralizeIL-22 or both IL-20 and IL-22 activity, such as the anti-human-IL-22RAneutralizing and monoclonal antibodies of the present invention, as wellas soluble IL-22RA receptors, are useful in therapeutic treatment ofother inflammatory diseases for example as antagonists to IL-22 or bothIL-20 and IL-22 in the treatment of atopic dermatitis, IBD, colitis,Endotoxemia, arthritis, rheumatoid arthritis, and psoriatic arthritisadult respiratory disease (ARD), septic shock, multiple organ failure,inflammatory lung injury such as asthma or bronchitis, bacterialpneumonia, psoriasis, eczema, atopic and contact dermatitis, andinflammatory bowel disease such as ulcerative colitis and Crohn'sdisease, and the like.

Within one aspect, the present invention provides a method of producingan antibody to a polypeptide comprising: inoculating an animal with apolypeptide selected from the group consisting of: (a) a polypeptideconsisting of the amino acid sequence of SEQ ID NO:3 from amino acidnumber 1 (Pro), to amino acid number 6 (Asp); (b) a polypeptideconsisting of the amino acid sequence of SEQ ID NO:3 from amino acidnumber 26 (Ser), to amino acid number 32 (Pro); (c) a polypeptideconsisting of the amino acid sequence of SEQ ID NO:3 from amino acidnumber 41 (Lys), to amino acid number 47 (Asp); (d) a polypeptideconsisting of the amino acid sequence of SEQ ID NO:2 from amino acidnumber 49 (Val), to amino acid number 62 (Cys); (e) a polypeptideconsisting of the amino acid sequence of SEQ ID NO:3 from amino acidnumber 41 (Lys) to amino acid number 62 (Cys); (f) a polypeptideconsisting of the amino acid sequence of SEQ ID NO:3 from amino acidnumber 84 (Ala) to amino acid number 97 (Ser); (g) a polypeptideconsisting of the amino acid sequence of SEQ ID NO:3 from amino acidnumber 103 (Thr) to amino acid number 108 (Asp); (h) a polypeptideconsisting of the amino acid sequence of SEQ ID NO:3 from amino acidnumber 130 (Arg) to amino acid number 135 (His); (i) a polypeptideconsisting of the amino acid sequence of SEQ ID NO:3 from amino acidnumber 164 (Gly) to amino acid number 166 (Lys); (j) a polypeptideconsisting of the amino acid sequence of SEQ ID NO:3 from amino acidnumber 175 (Tyr), to amino acid number 179 (Glu); (k) a polypeptideconsisting of the amino acid sequence of SEQ ID NO:3 from amino acidnumber 193 (Lys) to amino acid number 196 (Ala); (1) a polypeptideconsisting of the amino acid sequence of SEQ ID NO:3 from amino acidnumber 203 (Lys) to amino acid number 209 (Thr); and (m) a polypeptideconsisting of the amino acid sequence of SEQ ID NO:3; and (n) apolypeptide consisting of the amino acid sequence of SEQ ID NO:4; andwherein the polypeptide elicits an immune response in the animal toproduce the antibody; and isolating the antibody from the animal; andwherein the antibody specifically binds to an IL-22RA polypeptide (SEQID NO:2 or SEQ ID NO:3); and reduces the activity of either IL-20 (SEQID NO:8) or IL-22 (SEQ ID NO:6). In one embodiment the method is asdescribed above, wherein the antibody produced by the method reduces thepro-inflammatory activity of either IL-20 (SEQ ID NO:8) or IL-22 (SEQ IDNO:6). In another embodiment the method is as described above, whereinthe antibody produced by the method neutralizes the interaction ofeither IL-20 (SEQ ID NO:8) or IL-22 (SEQ ID NO:6) with IL-22RA (SEQ IDNO:2). In another embodiment the method is as described above, whereinthe neutralization by the antibody is measured by showing neutralizationof either IL-20 (SEQ ID NO:8) or IL-22 (SEQ ID NO:6) in an in vitro acell-based neutralization assay. In another embodiment the method is asdescribed above, wherein the antibody produced by the method reduces thepro-inflammatory activity of both IL-20 (SEQ ID NO:8) and IL-22 (SEQ IDNO:6). In another embodiment the method is as described above, whereinthe antibody produced by the method neutralizes the interaction of bothIL-20 (SEQ ID NO:8) and IL-22 (SEQ ID NO:6) with IL-22RA (SEQ ID NO:2).In another embodiment the method is as described above, wherein theneutralization by the antibody is measured by showing neutralization ofboth IL-20 (SEQ ID NO:8) and IL-22 (SEQ ID NO:6) in an in vitro acell-based neutralization assay.

Within another aspect, the present invention provides an antibodyproduced by the method as disclosed herein, which binds to a polypeptideof SEQ ID NO:2 or SEQ ID NO:3. In one embodiment the antibody is asdescribed above, wherein the antibody is (a) a polyclonal antibody, (b)a murine monoclonal antibody, (c) a humanized antibody derived from (b),(d) an antibody fragment, or (e) a human monoclonal antibody. In anotherembodiment the antibody is as described above, wherein the antibodyfurther comprises a radionuclide, enzyme, substrate, cofactor,fluorescent marker, chemiluminescent marker, peptide tag, magneticparticle, or toxin. In another embodiment the antibody is as describedabove, wherein the antibody further comprises PEGylation. In anotherembodiment the antibody is as described above, wherein the antibody is(a) a polyclonal antibody, (b) a murine monoclonal antibody, (c) ahumanized antibody derived from (b), (d) an antibody fragment, or (e) ahuman monoclonal antibody. In another embodiment the antibody is asdescribed above, wherein the antibody further comprises a radionuclide,enzyme, substrate, cofactor, fluorescent marker, chemiluminescentmarker, peptide tag, magnetic particle, drug, or toxin. In anotherembodiment the antibody is as described above, wherein the antibodyfurther comprises PEGylation.

Within another aspect, the present invention provides a antibody orantibody fragment that binds to a polypeptide comprising a sequence ofamino acid residues as shown in SEQ ID NO:3; and reduces thepro-inflammatory activity of either IL-20 (SEQ ID NO:8) or IL-22 (SEQ IDNO:6). In one embodiment the antibody or antibody fragment is asdescribed above, wherein the antibody or antibody fragment reduces thepro-inflammatory activity of both IL-20 (SEQ ID NO:8) and IL-22 (SEQ IDNO:6). In another embodiment the antibody or antibody fragment is asdescribed above, wherein the or antibody fragment is (a) a polyclonalantibody, (b) a murine monoclonal antibody, (c) a humanized antibodyderived from (b), (d) an antibody fragment, or (e) a human monoclonalantibody. In another embodiment the antibody or antibody fragment is asdescribed above, wherein the antibody further comprises a radionuclide,enzyme, substrate, cofactor, fluorescent marker, chemiluminescentmarker, peptide tag, magnetic particle, drug, or toxin. In anotherembodiment the antibody or antibody fragment is as described above,wherein the antibody further comprises PEGylation. In another embodimentthe antibody or antibody fragment is as described above, wherein the orantibody fragment is (a) a polyclonal antibody, (b) a murine monoclonalantibody, (c) a humanized antibody derived from (b), (d) an antibodyfragment, or (e) a human monoclonal antibody. In another embodiment theantibody or antibody fragment is as described above, wherein theantibody further comprises a radionuclide, enzyme, substrate, cofactor,fluorescent marker, chemiluminescent marker, peptide tag, magneticparticle, drug, or toxin. In another embodiment the antibody or antibodyfragment is as described above, wherein the antibody further comprisesPEGylation.

Within another aspect, the present invention provides a method forreducing or inhibiting either IL-22-induced or IL-20-inducedproliferation or differentiation of hematopoietic cells andhematopoietic cell progenitors comprising culturing bone marrow orperipheral blood cells with a composition comprising an amount of anantibody as disclosed herein sufficient to reduce proliferation ordifferentiation of the hematopoietic cells in the bone marrow orperipheral blood cells as compared to bone marrow or peripheral bloodcells cultured in the absence of the antibody. In one embodiment themethod is as described above, wherein the hematopoietic cells andhematopoietic progenitor cells are lymphoid cells. In another embodimentthe method is as described above, wherein the lymphoid cells aremacrophages or T cells.

Within another aspect, the present invention provides a method ofreducing IL-22-induced or IL-20-induced inflammation comprisingadministering to a mammal with inflammation an amount of a compositionof an antibody as disclosed herein sufficient to reduce inflammation.

Within another aspect, the present invention provides a method forreducing or inhibiting IL-22-induced and IL-20-induced proliferation ordifferentiation of hematopoietic cells and hematopoietic cellprogenitors comprising culturing bone marrow or peripheral blood cellswith a composition comprising an amount of an antibody as disclosedherein sufficient to reduce proliferation or differentiation of thehematopoietic cells in the bone marrow or peripheral blood cells ascompared to bone marrow or peripheral blood cells cultured in theabsence of the antibody. In one embodiment the method is as describedabove, wherein the hematopoietic cells and hematopoietic progenitorcells are lymphoid cells. In another embodiment the method is asdescribed above, wherein the lymphoid cells are macrophages or T cells.

Within another aspect, the present invention provides a method ofreducing IL-22-induced and IL-20-induced inflammation comprisingadministering to a mammal with inflammation an amount of a compositionof an antibody as disclosed herein sufficient to reduce inflammation.

Within another aspect, the present invention provides a method forreducing or inhibiting IL-22-induced and IL-20-induced proliferation ordifferentiation of hematopoietic cells and hematopoietic cellprogenitors comprising culturing bone marrow or peripheral blood cellswith a composition comprising an amount of an antibody or antibodyfragment as disclosed herein sufficient to reduce proliferation ordifferentiation of the hematopoietic cells in the bone marrow orperipheral blood cells as compared to bone marrow or peripheral bloodcells cultured in the absence of the antibody or antibody fragment. Inanother embodiment the method is as described above, wherein thehematopoietic cells and hematopoietic progenitor cells are lymphoidcells. In another embodiment the method is as described above, whereinthe lymphoid cells are macrophages or T cells.

Within another aspect, the present invention provides a method ofreducing IL-22-induced and IL-20-induced inflammation comprisingadministering to a mammal with inflammation an amount of a compositionof an antibody or antibody fragment as disclosed herein sufficient toreduce inflammation.

Within another aspect, the present invention provides a method forreducing or inhibiting IL-22-induced and IL-20-induced proliferation ordifferentiation of hematopoietic cells and hematopoietic cellprogenitors comprising culturing bone marrow or peripheral blood cellswith a composition comprising an amount of an antibody or antibodyfragment as disclosed herein sufficient to reduce proliferation ordifferentiation of the hematopoietic cells in the bone marrow orperipheral blood cells as compared to bone marrow or peripheral bloodcells cultured in the absence of the antibody. In another embodiment themethod is as described above, wherein the hematopoietic cells andhematopoietic progenitor cells are lymphoid cells. In another embodimentthe method is as described above, wherein the lymphoid cells aremacrophages or T cells.

Within another aspect, the present invention provides a method ofreducing IL-22-induced and IL-20-induced inflammation comprisingadministering to a mammal with inflammation an amount of a compositionof an antibody or antibody fragment as disclosed herein sufficient toreduce inflammation.

Within another aspect, the present invention provides a method ofsuppressing an inflammatory response in a mammal with inflammationcomprising: (1) determining a level of serum amyloid A protein; (2)administering a composition comprising an antibody according to anantibody or antibody fragment described herein in an acceptablepharmaceutical vehicle; (3) determining a post administration level ofserum amyloid A protein; (4) comparing the level of serum amyloid Aprotein in step (1) to the level of serum amyloid A protein in step (3),wherein a lack of increase or a decrease in serum amyloid A proteinlevel is indicative of suppressing an inflammatory response.

Within another aspect, the present invention provides a method oftreating a mammal afflicted with an inflammatory disease in which IL-22or IL-20 plays a role, comprising: administering an antagonist of IL-22or IL-20 to the mammal such that the inflammation is reduced, whereinthe antagonist comprises (i) an antibody, antibody fragment, or bindingpolypeptide that specifically binds a polypeptide or polypeptidefragment of IL-22RA (SEQ ID NO:3) or (ii) a polypeptide or polypeptidefragment of IL-22RA (SEQ ID NO:3); and wherein the inflammatory activityof either IL-22 (SEQ ID NO:6) or IL-20 (SEQ ID NO:8) is reduced. In oneembodiment the method is as described above, wherein the disease is achronic inflammatory disease. In another embodiment the method is asdescribed above, wherein the disease is a chronic inflammatory diseasecomprising inflammatory bowel disease, ulcerative colitis, Crohn'sdisease, arthritis, atopic dermatitis, or psoriasis. In anotherembodiment the method is as described above, wherein the disease is anacute inflammatory disease. In another embodiment the method is asdescribed above, wherein the disease is an acute inflammatory diseasecomprising endotoxemia, septicemia, toxic shock syndrome or infectiousdisease. In another embodiment the method is as described above, whereinthe antibody, antibody fragment, or binding polypeptide furthercomprises a radionuclide, enzyme, substrate, cofactor, fluorescentmarker, chemiluminescent marker, peptide tag, magnetic particle, drug,or toxin.

Within another aspect, the present invention provides a method oftreating a mammal afflicted with an inflammatory disease in which IL-22and IL-20 plays a role, comprising: administering an antagonist of bothIL-22 and IL-20 to the mammal such that the inflammation is reduced,wherein the antagonist comprises (i) an antibody, antibody fragment, orbinding polypeptide that specifically binds a polypeptide or polypeptidefragment of IL-22RA (SEQ ID NO:3) or (ii) a polypeptide or polypeptidefragment of IL-22RA (SEQ ID NO:3); and wherein the inflammatory activityof both IL-22 (SEQ ID NO:6) and IL-20 (SEQ ID NO:8) is reduced. In oneembodiment the method is as described above, wherein the disease is achronic inflammatory disease. In another embodiment the method is asdescribed above, wherein the disease is a chronic inflammatory diseasecomprising inflammatory bowel disease, ulcerative colitis, Crohn'sdisease, arthritis, atopic dermatitis, or psoriasis. In anotherembodiment the method is as described above, wherein the disease is anacute inflammatory disease. In another embodiment the method is asdescribed above, wherein the disease is an acute inflammatory diseasecomprising endotoxemia, septicemia, toxic shock syndrome or infectiousdisease. In another embodiment the method is as described above, whereinthe antibody, antibody fragment, or binding polypeptide furthercomprises a radionuclide, enzyme, substrate, cofactor, fluorescentmarker, chemiluminescent marker, peptide tag, magnetic particle, drug,or toxin.

Within another aspect, the present invention provides an antibodycomprising a monoclonal antibody that specifically binds to an antigenicepitope of human IL-22RA (SEQ ID NO:3) selected from the groupconsisting of: (a) an epitope consisting of the amino acid sequence ofSEQ ID NO:3 from amino acid number 1 (Pro), to amino acid number 6(Asp); (b) an epitope consisting of the amino acid sequence of SEQ IDNO:3 from amino acid number 26 (Ser), to amino acid number 32 (Pro); (c)an epitope consisting of the amino acid sequence of SEQ ID NO:3 fromamino acid number 41 (Lys), to amino acid number 47 (Asp); (d) anepitope consisting of the amino acid sequence of SEQ ID NO:2 from aminoacid number 49 (Val), to amino acid number 62 (Cys); (e) an epitopeconsisting of the amino acid sequence of SEQ ID NO:3 from amino acidnumber 41 (Lys) to amino acid number 62 (Cys); (f) an epitope consistingof the amino acid sequence of SEQ ID NO:3 from amino acid number 84(Ala) to amino acid number 97 (Ser); (g) an epitope consisting of theamino acid sequence of SEQ ID NO:3 from amino acid number 103 (Thr) toamino acid number 108 (Asp); (h) an epitope consisting of the amino acidsequence of SEQ ID NO:3 from amino acid number 130 (Arg) to amino acidnumber 135 (His); (i) an epitope consisting of the amino acid sequenceof SEQ ID NO:3 from amino acid number 164 (Gly) to amino acid number 166(Lys); (j) an epitope consisting of the amino acid sequence of SEQ IDNO:3 from amino acid number 175 (Tyr), to amino acid number 179 (Glu);(k) an epitope consisting of the amino acid sequence of SEQ ID NO:3 fromamino acid number 193 (Lys) to amino acid number 196 (Ala); (1) anepitope consisting of the amino acid sequence of SEQ ID NO:3 from aminoacid number 203 (Lys) to amino acid number 209 (Thr); and (m) an epitopeconsisting of the amino acid sequence of SEQ ID NO:3; and (n) an epitopeconsisting of the amino acid sequence of SEQ ID NO:4; and wherein theantibody reduces or neutralizes the activity of either human IL-22 (SEQID NO:6) or IL-20 (SEQ ID NO:8). In one embodiment the antibody is asdescribed above, wherein the antibody reduces or neutralizes theactivity of both human IL-22 (SEQ ID NO:6) and IL-20 (SEQ ID NO:8). Inanother embodiment the antibody is as described above, wherein theantibody is selected from the group consisting of: (a) a murinemonoclonal antibody, (b) a humanized antibody derived from (a), (c) anantibody fragment, and (d) a human monoclonal antibody. In anotherembodiment the antibody is as described above, wherein the antibodyfurther comprises PEGylation. In another embodiment the antibody is asdescribed above, wherein the antibody is selected from the groupconsisting of: (a) a murine monoclonal antibody, (b) a humanizedantibody derived from (a), (c) an antibody fragment, and (d) a humanmonoclonal antibody. In another embodiment the antibody is as describedabove, wherein the antibody further comprises PEGylation.

Within another aspect, the present invention provides a method oftreating a pathological condition in a subject associated with IL-22RAactivity comprising administering an effective amount of the antibody asdisclosed herein, thereby treating said pathological condition. In oneembodiment the method is as described above, wherein said pathologicalcondition is a chronic inflammatory condition. In another embodiment themethod is as described above, wherein said chronic inflammatorycondition comprising inflammatory bowel disease, ulcerative colitis,Crohn's disease, arthritis, atopic dermatitis, or psoriasis. In anotherembodiment the method is as described above, wherein said pathologicalcondition is an acute inflammatory condition. In another embodiment themethod is as described above, wherein said acute inflammatory conditioncomprises endotoxemia, septicemia, toxic shock syndrome, or infectiousdisease.

Within another aspect, the present invention provides a method oftreating a mammal afflicted with an inflammatory disease in whichIL-22RA plays a role, comprising: administering an antagonist of IL-22RAto the mammal such that the inflammation is reduced, wherein theantagonist comprises an antibody, antibody fragment, or bindingpolypeptide that specifically binds a polypeptide or polypeptidefragment of IL-22RA (SEQ ID NO:3); and wherein the inflammatory activityis reduced. In one embodiment the method is as described above, whereinthe disease is a chronic inflammatory disease. In another embodiment themethod is as described above, wherein the disease is a chronicinflammatory disease comprising inflammatory bowel disease, ulcerativecolitis, Crohn's disease, arthritis, atopic dermatitis, or psoriasis. Inanother embodiment the method is as described above, wherein the diseaseis an acute inflammatory disease. In another embodiment the method is asdescribed above, wherein the disease is an acute inflammatory diseasecomprising endotoxemia, septicemia, toxic shock syndrome or infectiousdisease. In another embodiment the method is as described above, whereinthe antibody, antibody fragment, or binding polypeptide furthercomprises a radionuclide, enzyme, substrate, cofactor, fluorescentmarker, chemiluminescent marker, peptide tag, magnetic particle, drug,or toxin. In another embodiment the method is as described above,wherein the antibody, antibody fragment, or binding polypeptide furthercomprises, wherein the antibody further comprises PEGylation.

Within another aspect, the present invention provides a method ofreducing inflammation comprising administering to a mammal withinflammation an amount of a composition of an antibody as disclosedherein sufficient to reduce inflammation.

The invention is further illustrated by the following non-limitingexamples.

EXAMPLE 1 Purification of IL-22RA2-Fc4 Polypeptide From Transfected BHK570 Cells

Unless otherwise noted, all operations were carried out at 4° C. Thefollowing procedure was used for purifying IL-22RA2 polypeptide (maturesoluble receptor polypeptide from residues 23 to 231 of SEQ ID NO:13;polynucleotides as shown in SEQ ID NO:12) containing C-terminal fusionto human Fc4 (SEQ ID NO:14), designated IL-22RA2-Fc4. About 16,500 ml ofconditioned media from BHK 570 cells transfected with IL-22RA2-Fc4 wasfiltered through a 0.2 um sterilizing filter and then supplemented witha solution of protease inhibitors, to final concentrations of, 0.001 mMleupeptin (Boerhinger-Mannheim, Indianapolis, Ind.), 0.001 mM pepstatin(Boerhinger-Mannheim) and 0.4 mM Pefabloc (Boerhinger-Mannheim). A Porosprotein A50 column (20 ml bed volume, Applied Biosystems) was packed andwashed with 400 ml PBS (Gibco/BRL) The supplemented conditioned mediawas passed over the column with a flow rate of 15 ml/minute, followed bywashing with 800 ml PBS (BRL/Gibco). IL-22RA2-Fc4 was eluted from thecolumn with 0.1 M Glycine pH 3.0 and 5 ml fractions were collecteddirectly into 0.5 ml 2M Tris pH 7.8, to adjust the final pH to 7.4 inthe fractions.

Column performance was characterized through western blotting ofreducing SDS-PAGE gels of the starting media and column pass through.Western blotting used anti-human IgG HRP (Amersham) antibody, whichshowed an immunoreactive protein at 60,000 Da in the starting media,with nothing in the pass through, suggesting complete capture. Theprotein A50 eluted fractions were characterized by reducing SDS PAGEgel. This gel showed an intensely Coomassie stained band at 60,000 Da infractions 3 to 11. Fractions 3 to 11 were pooled.

Protein A 50 elution pool was concentrated from 44 ml to 4 ml using a30,000 Da Ultrafree Biomax centrifugal concentrator (15 ml volume,Millipore). A Sephacryl S-300 gel filtration column (175 ml bed volume;Pharmacia) was washed with 350 ml PBS (BRL/Gibco). The concentrated poolwas injected over the column with a flow rate of 1.5 ml/min, followed bywashing with 225 ml PBS (BRL/Gibco). Eluted peaks were collected into 2ml fractions.

Eluted fractions were characterized by reducing and non-reducing silverstained (Geno Technology) SDS PAGE gels. Reducing silver stained SDSPAGE gels showed an intensely stained band at 60,000 Da in fractions14-31, while non-reducing silver stained SDS PAGE gels showed anintensely stained band at 160,000 Da in fractions 14-31. Fractions 1-13showed many bands of various sizes. Fractions 14-31 were pooled,concentrated to 22 ml using 30,000 Da Ultrafree Biomax centrifugalconcentrator (15 ml volume, Millipore). This concentrate was filteredthrough a 0.2 μm Acrodisc sterilizing filter (Pall Corporation).

The protein concentration of the concentrated pooled fractions wasperformed by BCA analysis (Pierce, Rockford, Ill.) and the material wasaliquoted, and stored at −80° C. according to our standard procedures.The concentration of the pooled fractions was 1.50 mg/ml.

EXAMPLE 2 Construction of BaF3 Cells Expressing the CRF2-4 Receptor(BaF3/CRF2-4 Cells) and BaF3 Cells Expressing the CRF2-4 Receptor withthe IL-22RA Receptor (BaF3/CRF2-4/IL-22RA Cells)

BaF3 cells expressing the full-length CFR2-4 receptor were constructed,using 30 μg of a CFR2-4 expression vector, described below. The BaF3cells expressing the CFR2-4 receptor were designated as BaF3/CFR2-4.These cells were used as a control, and were further transfected withfull-length IL-22RA receptor (U.S. Pat. No. 5,965,704) and used toconstruct a screen for IL-22 activity as described below.

A. Construction of BaF3 Cells Expressing the CRF2-4 Receptor

The full-length cDNA sequence of CRF2-4 (Genbank Accession No. Z17227)was isolated from a Daudi cell line cDNA library, and then cloned intoan expression vector pZP7P.

BaF3, an interleukin-3 (IL-3) dependent pre-lymphoid cell line derivedfrom murine bone marrow (Palacios and Steinmetz, Cell 41: 727-734, 1985;Mathey-Prevot et al., Mol. Cell. Biol. 6: 4133-4135, 1986), wasmaintained in complete media (RPMI medium (JRH Bioscience Inc., Lenexa,Kans.) supplemented with 10% heat-inactivated fetal calf serum, 2 ng/mlmurine IL-3 (mIL-3) (R & D, Minneapolis, Minn.), 2 mM L-GLUTAMAX-1™(Gibco BRL), 1 mM Sodium Pyruvate (Gibco BRL), and PSN antibiotics(GIBCO BRL)). Prior to electroporation, CRF2-4/pZP7P was prepared andpurified using a Qiagen Maxi Prep kit (Qiagen) as per manufacturer'sinstructions. For electroporation, BaF3 cells were washed once inserum-free RPMI media and then resuspended in serum-free RPMI media at acell density of 10⁷ cells/ml. One ml of resuspended BaF3 cells was mixedwith 30 μg of the CRF2-4/pZP7P plasmid DNA and transferred to separatedisposable electroporation chambers (GIBCO BRL). Following a 15-minuteincubation at room temperature the cells were given two serial shocks(800 1Fad/300 V.; 1180 1Fad/300 V.) delivered by an electroporationapparatus (CELL-PORATOR™; GIBCO BRL). After a 5-minute recovery time,the electroporated cells were transferred to 50 ml of complete media andplaced in an incubator for 15-24 hours (37° C., 5% CO₂). The cells werethen spun down and resuspended in 50 ml of complete media containing 2μg/ml puromycin in a T-162 flask to isolate the puromycin-resistantpool. Pools of the transfected BaF3 cells, hereinafter calledBaF3/CRF2-4 cells, were assayed for signaling capability as describedbelow. Moreover these cells were further transfected with IL-22RAreceptor as described below.

B. Construction of BaF3 Cells Expressing CRF2-4 and IL-22RA Receptors

BaF3/CRF2-4 cells expressing the full-length IL-22RA receptor wereconstructed as per above, using 30 μg of a IL-22RA expression vector.Following recovery, transfectants were selected using 200 μg/ml zeocinand 2 μg/ml puromycin. The BaF3/CRF2-4 cells expressing the IL-22RAreceptor were designated as BaF3/CRF2-4/IL-22RA cells. These cells wereused to screen for IL-22 activity as well as IL-22RA2 antagonistactivity described herein.

EXAMPLE 3 Screening for IL-22 Antagonist Activity UsingBaF3/CRF2-4/IL-22RA Cells Using an Alamar Blue Proliferation Assay

A. Screening for IL-22 Activity Using BaF3/CRF2-4/IL-22RA Cells Using anAlamar Blue Proliferation Assay

Purified IL-22-CEE (Example 4) was used to test for the presence ofproliferation activity as described below. Purified IL-22RA2-Fc4(Example 1) was used to antagonize the proliferative response of theIL-22 in this assay as described below.

BaF3/CRF2-4/IL-22RA cells were spun down and washed in the completemedia, (RPMI medium (JRH Bioscience Inc., Lenexa, Kans.) supplementedwith 10% heat-inactivated fetal calf serum, 2 ng/ml murine IL-3 (mIL-3)(R & D, Minneapolis, Minn.), 2 mM L-GLUTAMAX-1™ (Gibco BRL), 1 mM SodiumPyruvate (Gibco BRL), and PSN antibiotics (GIBCO BRL)), but withoutmIL-3 (hereinafter referred to as “mIL-3 free media”). The cells werespun and washed 3 times to ensure the removal of the mIL-3. Cells werethen counted in a hemacytometer. Cells were plated in a 96-well formatat 5000 cells per well in a volume of 100 μl per well using the mIL-3free media.

Proliferation of the BaF3/CRF2-4/IL-22RA cells was assessed usingIL-22-CEE protein diluted with mIL-3 free media to 50, 10, 2, 1, 0.5,0.25, 0.13, 0.06 ng/ml concentrations. 100 μl of the diluted protein wasadded to the BaF3/CRF2-4/IL-22RA cells. The total assay volume is 200μl. The assay plates were incubated at 37° C., 5% CO₂ for 3 days atwhich time Alamar Blue (Accumed, Chicago, Ill.) was added at 20 μl/well.Plates were again incubated at 37° C., 5% CO₂ for 24 hours. Alamar Bluegives a fluourometric readout based on number of live cells, and is thusa direct measurement of cell proliferation in comparison to a negativecontrol. Plates were again incubated at 37° C., 5% CO₂ for 24 hours.Plates were read on the FMAX™ plate reader (Molecular Devices Sunnyvale,Calif.) using the SOFTMAX™ Pro program, at wavelengths 544 (Excitation)and 590 (Emmission). Results confirmed the dose-dependent proliferativeresponse of the BaF3/CRF2-4/IL-22RA cells to IL-22-CEE. The response, asmeasured, was approximately 15-fold over background at the high end of50 ng/ml down to a 2-fold induction at the low end of 0.06 ng/ml. TheBaF3 wild type cells, and BaF3/CRF2-4 cells did not proliferate inresponse to IL-22-CEE, showing that IL-22 is specific for theCRF2-4/IL-22RA heterodimeric receptor.

In order to determine if IL-22RA2 is capable of antagonizing IL-22activity, the assay described above was repeated using purified solubleIL-22RA2/Fc4. When IL-22 was combined with IL-22RA2 at 10 μg/ml, theresponse to IL-22 at all concentrations was brought down to background.That the presence of soluble IL-22RA2 ablated the proliferative effectsof IL-22 demonstrates that it is a potent antagonist of the IL-22ligand. This assay can be used to test other antagonists of IL-22activity described herein, such as anti-IL-22RA antibodies.

EXAMPLE 4 Purification of IL-22-CEE from BHK 570 Cells

Unless otherwise noted, all operations were carried out at 4° C. Thefollowing procedure was used for purifying IL-22 polypeptide containingC-terminal GluGlu (EE) tag (SEQ ID NO:15; or SEQ ID NO:16). Conditionedmedia from BHK cells expressing IL-22-CEE was concentrated with anAmicon S10Y3 spiral cartridge on a ProFlux A30. A Protease inhibitorsolution was added to the concentrated conditioned media to finalconcentrations of 2.5 mM ethylenediaminetetraacetic acid (EDTA, SigmaChemical Co. St. Louis, Mo.), 0.003 mM leupeptin (Boehringer-Mannheim,Indianapolis, Ind.), 0.001 mM pepstatin (Boehringer-Mannheim) and 0.4 mMPefabloc (Boehringer-Mannheim). Samples were removed for analysis andthe bulk volume was frozen at −80° C. until the purification wasstarted. Total target protein concentrations of the concentratedconditioned media were determined via SDS-PAGE and Western blot analysiswith the anti-EE HRP conjugated antibody.

About 100 ml column of anti-EE G-Sepharose (prepared as described below)was poured in a Waters AP-5, 5 cm×10 cm glass column. The column wasflow packed and equilibrated on a BioCad Sprint (PerSeptive BioSystems,Framingham, Mass.) with phosphate buffered saline (PBS) pH 7.4. Theconcentrated conditioned media was thawed, 0.2 micron sterile filtered,pH adjusted to 7.4, then loaded on the column overnight with about 1ml/minute flow rate. The column was washed with 10 column volumes (CVs)of phosphate buffered saline (PBS, pH 7.4), then plug eluted with 200 mlof PBS (pH 6.0) containing 0.5 mg/ml EE peptide (Anaspec, San Jose,Calif.) at 5 ml/minute. The EE peptide used has the sequence EYMPME (SEQID NO:15). The column was washed for 10 CVs with PBS, then eluted with 5CVs of 0.2M glycine, pH 3.0. The pH of the glycine-eluted column wasadjusted to 7.0 with 2 CVs of 5×PBS, then equilibrated in PBS (pH 7.4).Five ml fractions were collected over the entire elution chromatographyand absorbance at 280 and 215 nM were monitored; the pass through andwash pools were also saved and analyzed. The EE-polypeptide elution peakfractions were analyzed for the target protein via SDS-PAGE Silverstaining and Western Blotting with the anti-EE HRP conjugated antibody.The polypeptide elution fractions of interest were pooled andconcentrated from 60 ml to 5.0 ml using a 10,000 Dalton molecular weightcutoff membrane spin concentrator (Millipore, Bedford, Mass.) accordingto the manufacturer's instructions.

To separate IL-22-CEE from other co-purifying proteins, the concentratedpolypeptide elution pooled fractions were subjected to a POROS HQ-50(strong anion exchange resin from PerSeptive BioSystems, Framingham,Mass.) at pH 8.0. A 1.0×6.0 cm column was poured and flow packed on aBioCad Sprint. The column was counter ion charged then equibrated in 20mM TRIS pH 8.0 (Tris (Hydroxymethyl Aminomethane)). The sample wasdiluted 1:13 (to reduce the ionic strength of PBS) then loaded on thePoros HQ column at 5 ml/minute. The column was washed for 10 CVs with 20mM Tris pH 8.0 then eluted with a 40 CV gradient of 20 mM Tris/1 Msodium chloride (NaCl) at 10 ml/minute. 1.5 ml fractions were collectedover the entire chromatography and absorbance at 280 and 215 nM weremonitored. The elution peak fractions were analyzed via SDS-PAGE Silverstaining. Fractions of interest were pooled and concentrated to 1.5-2 mlusing a 10,000 Dalton molecular weight cutoff membrane spin concentrator(Millipore, Bedford, Mass.) according to the manufacturer'sinstructions.

To separate IL-22-CEE polypeptide from free EE peptide and anycontaminating co-purifying proteins, the pooled concentrated fractionswere subjected to size exclusion chromatography on a 1.5×90 cm SephadexS200 (Pharmacia, Piscataway, N.J.) column equilibrated and loaded in PBSat a flow rate of 1.0 ml/min using a BioCad Sprint. 1.5 ml fractionswere collected across the entire chromatography and the absorbance at280 and 215 nM were monitored. The peak fractions were characterized viaSDS-PAGE Silver staining, and only the most pure fractions were pooled.This material represented purified IL-22-CEE polypeptide.

This purified material was finally subjected to a 4 ml ActiClean Etox(Sterogene) column to remove any remaining endotoxins. The sample waspassed over the PBS equilibrated gravity column four times then thecolumn was washed with a single 3 ml volume of PBS, which was pooledwith the “cleaned” sample. The material was then 0.2 micron sterilefiltered and stored at −80° C. until it was aliquoted.

On Western blotted, Coomassie Blue and Silver stained SDS-PAGE gels, theIL-22-CEE polypeptide was one major band. The protein concentration ofthe purified material was performed by BCA analysis (Pierce, Rockford,Ill.) and the protein was aliquoted, and stored at −80° C. according tostandard procedures.

To prepare anti-EE Sepharose, a 100 ml bed volume of protein G-Sepharose(Pharmacia, Piscataway, N.J.) was washed 3 times with 100 ml of PBScontaining 0.02% sodium azide using a 500 ml Nalgene 0.45 micron filterunit. The gel was washed with 6.0 volumes of 200 mM triethanolamine, pH8.2 (TEA, Sigma, St. Louis, Mo.), and an equal volume of EE antibodysolution containing 900 mg of antibody was added. After an overnightincubation at 4° C., unbound antibody was removed by washing the resinwith 5 volumes of 200 mM TEA as described above. The resin wasresuspended in 2 volumes of TEA, transferred to a suitable container,and dimethylpimilimidate-2HCl (Pierce, Rockford, Ill.) dissolved in TEA,was added to a final concentration of 36 mg/ml of protein G-Sepharosegel. The gel was rocked at room temperature for 45 min and the liquidwas removed using the filter unit as described above. Nonspecific siteson the gel were then blocked by incubating for 10 min. at roomtemperature with 5 volumes of 20 mM ethanolamine in 200 mM TEA. The gelwas then washed with 5 volumes of PBS containing 0.02% sodium azide andstored in this solution at 4° C.

EXAMPLE 5 In Vivo Affects of IL-22 Polypeptide

Mice (female, C57BL/6N, 8 weeks old; Charles River Labs, Kingston, N.Y.)were divided into three groups. An adenovirus expressing an IL-22polypeptide (SEQ ID NO:6) was previously made using standard methods. Onday 0, parental or IL-22 adenovirus was administered to the first (n=8)and second (n=8) groups, respectively, via the tail vein, with eachmouse receiving a dose of ˜1×10¹¹ particles in ˜0.1 ml volume. The thirdgroup (n=8) received no treatment. On days 12, mice were weighed andblood was drawn from the mice. Samples were analyzed for complete bloodcount (CBC) and serum chemistry. Statistically significant elevations inneutrophil and platelet counts were detected in the blood samples fromthe IL-22 adenovirus administered group relative to the parentaladenovirus treated group. Also, lymphocyte and red blood cell countswere significantly reduced from the IL-22 adenovirus administered grouprelative to the parental adenovirus treated group. In addition, theIL-22 adenovirus treated mice decreased in body weight, while parentaladenovirus treated mice gained weight. Also the serum IL-22 level wasincreased and the glucose level decreased at day 3. In summary, IL-22adeno-mice displayed acute phase resonse that can also be initiated byother pro-inflammatory cytokines such as TNF-alpha, IL-1beta, and gp130cytokines. The acute phase response is the set of immediate inflammatoryresponses initiated by pattern recognition molecules. The acute phaseproteins provide enhanced protection against microorganisms and modifyinflammatory responses by effects on cell trafficking and mediatorrelease. For example, SAA has potent leukocyte activating fuctionincluding induction of chemotaxis, enhancement of leukocyte adhesion toendothelial cells, and increased phagocytosis. Understanding the factorsthat initiate and alter the magnitude and duration of the acute phaseresponse respresents an important step in the development of newtherapies for infectious and inflammatory diseases.

The results suggested that IL-22 affects hematopoiesis, i.e., blood cellformation in vivo. As such, IL-22 could have biological activitieseffecting different blood stem cells, thus resulting increase ordecrease of certain differentiated blood cells in a specific lineage.For instance, IL-22 appears to reduce lymphocytes, which is likely dueto inhibition of the committed progenitor cells that give rise tolymphoid cells. IL-22 also decreases red blood cells, supporting thenotion that IL-22 could play a role in anemia, infection, inflammation,and/or immune diseases by influencing blood cells involved in theseprocess. Antagnists against IL-22, such as antibodies or its solublereceptor IL-22RA2, could be used as therapeutic reagents in thesediseases.

Moreover, these experiments using IL-22 adenovirus in mice suggest thatIL-22 over-expression increases the level of neutrophils and plateletsin vivo. It is conceivable that there are other factors (such ascytokines and modifier genes) involved in the responses to IL-22 in thewhole animal system. Nevertheless, these data strongly support theinvolvement of IL-22 in hematopoiesis. Thus, IL-22 and its receptors aresuitable reagents/targets for the diagnosis and treatment in variety ofdisorders, such as inflammation, immune disorders, infection, anemia,hematopoietic and other cancers, and the like.

EXAMPLE 6 IL-22-Expressing Transgenic Mice

A. Generation of Transgenic Mice Expressing Mouse IL-22

DNA fragments from a transgenic vector containing 5′ and 3′ flankingsequences of the lymphoid specific EμLCK promoter, mouse IL-22 (SEQ IDNO:10; polypeptide shown in SEQ ID NO:11), the rat insulin II intron,IL-22 cDNA and the human growth hormone poly A sequence were preparedusing standard methods, and used for microinjection into fertilizedB6C3f1 (Taconic, Germantown, N.Y.) murine oocytes, using a standardmicroinjection protocol. See, Hogan, B. et al., Manipulating the MouseEmbryo. A Laboratory Manual, Cold Spring Harbor Laboratory Press, 1994.

Twenty-five mice transgenic for mouse IL-22 with the lymphoid-specificEμLCK promoter were identified among 154 pups. Eleven of the transgenicpups died within hours of birth, 9 transgenic pups with a shinyappearance were necropsied the day of birth, and 2 grew to adulthood.Expression levels were low in one adult animal. Tissues from thenecropsied pups were prepared and histologically examined as describedbelow.

The shiny appearance of the neonate pups appeared to be associated witha stiffening of the skin, as if they were drying out, resulting in areduction of proper nursing. Their movements became stiffened ingeneral.

B. Genotypic and Expression Analysis from Transgenic Mice

From the mouse IL-22 transgenic line driven by the EμLck promoter,described above, newborn pups were observed for abnormalities on day one(day of birth) and sacrificed for tissue collection. All pups were givena unique ear tag number, and those designated as having a shiny skinphenotype at the time of sacrifice were noted. Of the twelve pups, sixwere observed to have the shiny skin phenotype, with two designated as“severe” phenotypes. Severe phenotypes were defined as small pups withlittle mobility whose skin was especially shiny and very dry. Skin wascollected from the left lateral side of each pup, and frozen inTissue-Tek embedding medium.

Genotyping confirmed that shiny skin was a good indicator of transgenicstatus, although no expression data was collected. Frozen skin blockswere sectioned to 7 microns on a cryostat and stained to look for thepresence of CD3, CD4, CD8, mouse macrophages, B-cells, CD80, and MHCclass II. The staining protocol involved binding of commerciallyavailable antibodies to the tissue, detection with a peroxidase labeledsecondary antibody, and DAB chromogen reaction to visualize staining.

Transgenic animals were found to be higher in MHC class II and CD80,which stain for antigen-presenting cells and dendritic cellsrespectively. The macrophage marker also detected more cells in thesevere and non-severe transgenics than in the wild type animals,although the distribution of these cells was very localized in the highdermis. Animals classified as severe phenotypes had the most robuststaining with all three of these markers, showing a dramatic increase incell intensity and number when compared to the wild type. Thisvariability may be due to a difference in expression level of IL-22 inthese transgenic founder pups. The MHC class II positive cells werelocated in the lower dermis arranged in loose open clusters, while theCD80 positive cells were predominantly below the dermis either in orjust above the muscle/fat layer. These two cell populations do notappear to overlap. All other markers were of equivalent staining in allanimals. Toluidine blue staining for mast cells revealed slight to nodifference between wild type and transgenic animals.

C. Microscopic Evaluation of Tissues from Transgenic Mice: IL-22 Tg withEuLck Promoter has a Neonatal Lethal-Histology

On the day of birth, pups from litters containing IL-22 transgenics werehumanely euthanized and the whole body immersion fixed in 10% bufferedformalin. Six transgenic and two non-transgenic pups were submitted forfurther workup. Four of the six transgenics were noted to have shinyskin at the time of euthanasia. The fixed tissues were trimmed into 5sections (longitudinal section of the head and cross sections of theupper and lower thorax and upper and lower abdomen). The tissues wereembedded in paraffin, routinely processed, sectioned at 5 um (Jung 2065Supercut microtome, Leica Microsystems, Wetzlar, Germany) and stainedwith H&E. The stained tissues were evaluated under a light microscope(Nikon Eclipse E600, Nikon Inc., Melville, N.Y.) by a board (ACVP)certified veterinary pathologist.

On microscopic examination, the epidermis of two of the transgenic pupswas observed to be thicker than the epidermis of the other six miceincluding the controls. No other abnormalities were noted in the skinand other tissues of any of the mice. Representative areas of skin fromcorresponding regions of the thorax and abdomen were imaged with the 40×objective lens and with a CoolSnap digital camera (Roper Scientific,Inc., San Diego, Calif.) that was attached to the microscope. Thethickness of the epidermis was then determined using histomorphometrysoftware (Scion Image for Windows (NIH Image), Scion Corp., Frederick,Md., v. B4.0.2). The results shown in Table 5 were as follows:

TABLE 5 Average thoracic skin Average abdominal skin Genotype/phenotypethickness (μm) thickness (μm) Non-transgenic/normal 5.2 5.4Transgenic/non-shiny 5.0 6.7 Transgenic/shiny 8.2 7.4 Transgenic/all 7.17.1

There were insufficient numbers of mice to determine statisticalsignificance; however, the transgenics, especially those with shinyskin, tended to have a thicker epidermis than the non-shiny transgenicsand non-transgenic controls. The shiny transgenics may have a higherexpression level of IL-22 than the non-shiny transgenics; however,expression levels were not determined for these mice. These suggested arole for IL-22 in psoriasis, psoriatic arthritis, or other inflammatoryskin conditions or other inflammatory diseases.

EXAMPLE 7 In Vivo Affects of IL-22 Polypeptide

A. Mice Infected with IL-22 Adenovirus Show Induction of SAA

Mice (female, C57BL/6N, 8 weeks old; Charles River Labs, Kingston, N.Y.)were divided into three groups. An adenovirus expressing an IL-22polypeptide (SEQ ID NO:6) was previously made using standard methods. Onday 0, parental or IL-22 adenovirus was administered to the first (n=8)and second (n=8) groups, respectively, via the tail vein, with eachmouse receiving a dose of ˜1×10¹¹ particles in ˜0.1 ml volume. The thirdgroup (n=8) received no treatment. On day 12, mice were weighed andblood was drawn from the mice. On day 20 of the study, mice weresacrificed, body weight was recorded, and blood and tissues werecollected for analysis.

All blood samples were analyzed for complete blood count (CBC) and serumchemistry. At both day 12 and 20, statistically significant elevationsin neutrophil and platelet counts were detected in the blood samplesfrom the IL-22 adenovirus administered group relative to the parentaladenovirus treated group. Also, lymphocyte counts were significantlyreduced from the IL-22 adenovirus administered group relative to theparental adenovirus treated group at day 12, but at day 20 the oppositeeffect was observed. In addition, the IL-22 adenovirus treated micedecreased in body weight, while parental adenovirus treated mice gainedweight. Glucose was significantly reduced at both time points in theserum samples from the IL-22 adenovirus administered group relative tothe parental adenovirus treated group. Serum albumin was alsosignificantly reduced at both time points. Blood urea nitrogen levelswere significantly reduced at day 20. Serum globulin levels weresignificantly increased the IL-22 adenovirus administered group relativeto the parental adenovirus treated group at both time points.Microscopically, one observed histomorphological change attributed toIL-22 was tubular regeneration in the kidney. While not uncommon inmice, there was an increased incidence and severity in this group ofanimals. Nephropathy is characterized as multifocal areas of basophiliaof cortical tubular epithelial cells.

An additional experiment, identical in design to the one describedabove, was carried out in order to verify results and collect additionalsamples. In this study, body weight was recorded every three days, bloodwas collected from the mice 3 days following adenovirus injection, andmice were sacrificed for blood and tissue collection on day 10 (n=4 pergroup) and day 20 (n=4 per group). Elevated neutrophil and plateletcounts were again detected in blood samples from the IL-22 adenovirusadministered group relative to the parental adenovirus treated group.This effect was evident for neutrophils by day 3, but platelet count wasnot significantly different until day 10. Also, lymphocyte counts weresignificantly reduced from the IL-22 adenovirus administered grouprelative to the parental adenovirus treated group at 3 and 10, but theywere not elevated on day 20 as in the previous study. Again, mice givenIL-22 adenovirus lost weight over the course of the study, while controlvirus treated and untreated mice gained weight. Serum chemistryparameters were consistent with the previous study. Histologicalfindings of tubular regeneration in the kidney associated with IL-22adenovirus treatment were also confirmed in this study. This wasconsistent with the additional finding of moderate proteinurea in micegiven IL-22 adenovirus (day 20).

The results suggested that IL-22 affects hematopoiesis, i.e., blood cellformation in vivo. As such, IL-22 could have biological activitieseffecting different blood stem cells, thus resulting in an increase ordecrease of certain differentiated blood cells in a specific lineage.For instance, IL-22 appears to reduce lymphocytes, which is likely dueto inhibition of the committed progenitor cells that give rise tolymphoid cells, supporting the notion that IL-22 could play a role inanemia, infection, inflammation, and/or immune diseases by influencingblood cells involved in these processes. Antagonists against IL-22, suchas antibodies or its soluble receptor IL-22RA2, could be used astherapeutic reagents in these diseases.

Moreover, these experiments using IL-22 adenovirus in mice suggest thatIL-22 over-expression increases the level of neutrophils and plateletsin vivo. It is conceivable that there are other factors (such ascytokines and modifier genes) involved in the responses to IL-22 in thewhole animal system. Nevertheless, these data strongly support theinvolvement of IL-22 in hematopoiesis. Thus, IL-22, anti-IL-22antibodies, IL-22RA soluble receptors (e.g., SEQ ID NO:3), andanti-IL-22RA antibodies are suitable reagents/targets for the diagnosisand treatment in variety of disorders, such as inflammation, immunedisorders, infection, anemia, hematopoietic and other cancers, and thelike.

Association of IL-22 expression with weight loss, appearance of acutephase protein SAA, and metabolic perturbations evidenced by decreasedserum glucose, albumin and urea nitrogen suggest that IL-22 is acytokine which acts early in certain inflammatory responses. Mice givenIL-22 adenovirus may represent a state of chronic inflammation, such asthat observed in IBD, ulcerative colitis, arthritis, psoriasis,psoriatic arthritis, asthma, and the like. Certain detrimentalinflammatory processes might be inhibited by use of an antagonist toIL-22, such as anti-IL-22 antibodies, and its receptors, such as IL-22RAsoluble receptors (e.g., SEQ ID NO:3), and anti-IL-22RA antibodies andthe like.

B. IL-22 is a Pro-inflammatory Cytokine: Serum Level of SAA inAdeno-IL-22 Mice:

An ELISA was performed to determine the level of SAA in IL-22-Adenomice, using a Mouse SAA Immunoassay Kit and protocol (BiosourceInternational, California, USA). Diluted standards and unknowns wereplated along with HRP-anti-mouse SAA into assay plates pre-coated withanti-mouse SAA antibody. Plates were incubated for one hour at 37degrees C. and then washed according to kit instructions. Plates weredeveloped for 15 minutes at room temperature using TMB and stopped with2M H₂S0₄. The absorbance at 450 nm was read using a Spectromax 190(Molecular Devices, California, USA). The resulting data was analyzedusing Softmax Pro (Molecular Devices, California, USA) and Excel(Microsoft Corp., Washington, USA).

Mice infected with IL-22-Adenovirus had highly elevated levels of mSAA,over 10-fold, relative to the Parental-Adenovirus control.

C. Flow Cytometry Analysis of IL-22-adenovirus Infected Mice

To analyze the effects of IL-22 expression in vivo by adenovirus, weisolated peripheral blood, spleen, and bone marrow from IL-22-adenovirusinfected C57BL/6N mice, at day 10 and day 20 after infection.Approximately 100 μl of blood was collected in heparinized tubes, thendepleted of red blood cells by hypotonic lysis (cells were lysed in 4.5ml dH₂O for ˜5 seconds before adding 1.5 ml 3.6% NaCl). Spleens werecrushed between two frosted glass slides, and the cells released werepassed over a Nytex membrane (cell strainer) and pelleted. Bone marrowwas obtained by crushing one femur in a mortar and pestle and passingthe cells over a cell strainer (Falcon). Cells were resuspended in FACSwash buffer (WB=HBSS/1% BSA/10 mM hepes), counted in trypan blue, and1×10⁶ viable cells of each type were aliquoted into 5 ml polystyrenetubes. Cells were washed and pelleted, then incubated for 20 min on icewith cocktails of fluorescently-labeled (FITC, PE, and CyChrome)monoclonal antibodies (PharMingen, San Diego, Calif.) recognizingvarious cell surface markers used to identify particular immune cellsubsets. These markers include the following (listed in the groups of 3we tested). For blood staining: CD3, Gr1, and B220; for spleen staining:CD62L, CD44, and CD3; CD21, CD23, and B220; IgD, IgM, and B220; CD11b,Gr1, and CD8; for bone marrow staining: CD11b, Gr1, CD3; IgD, IgM, andB220. Cells were washed with 1.5 ml WB and pelleted, then resuspended in0.4 ml of WB and analyzed on a FACScan using CellQuest software (BectonDickinson, Mountain View, Calif.).

We found that the fraction of neutrophils in the blood ofIL-22-adeno-treated mice was elevated 4-13 fold at Day 10 and 2-3-foldat Day 20. At Day 10, this difference resulted in a concomitant decreasein the fraction of lymphocytes and monocytes in the blood. In the bonemarrow, we found that the total number of B cells decreased ˜1.5-foldwhile the percentage of mature recirculating B cells increased and thetotal number of immature B cells dropped slightly at Day 10. At Day 20,many of these differences were not apparent, though we did find a slightincrease in the fraction of mature recirculating B cells. In the spleen,the total number of B cells decreased slightly (1.5-2-fold) on both daystested, while on Day 20, the fraction of marginal zone B cells(CD21+CD23-B220+) increased by 2-fold and the number of follicular Bcells (CD21+CD23+B220+) dropped 2-fold. Marginal zone B cells areconsidered to be the first line of defense against pathogens, as theyare more sensitive to B cell mitogens (e.g. LPS) than the more commonfollicular B cells, and when they encounter their cognate antigen theydifferentiate very quickly into antibody-secreting cells. It is possiblethat IL-22 either enhances the conversion of follicular to marginal zoneB cells, or that it selectively depletes the less mature follicularcells. The changes in B cell numbers found in the bone marrow mayreflect an enhanced differentiation of pre/pro and/or immature B cells,or an increased influx of recirculating B cells from the blood/spleen,and perhaps a coincident increase in export of immature B cells to theperiphery. The actual number of mature BM B cells does not increase, soIL-22 may not enhance their proliferation. Alternatively, IL-22 mayblock, reduce or inhibit differentiation of immature B cells and therebyincrease the relative representation of mature B cells.

D. IL-22RA2-Fc4 Neutralizes IL-22 Activity In Vivo: SAA ELISA ShowingSAA Expression Induced by IL-22 is Inhibited by IL-22RA2-Fc4 Injection:

To assess whether IL-22RA2 could inhibit the SAA induction by IL-22 mice(female, C3H/HEJ, 8 weeks old; Jackson Labs, Bar Harbor, Me.) weredivided into five groups of three animals each and treated by IPinjection of proteins as shown in Table 6 below:

TABLE 6 Group # IL-22 IL-22RA2 Group 1: — — Group 2: — 100 μg Group 3: 3μg — Group 4: 3 μg  20 μg Group 5: 3 μg 100 μg

The IL-22RA2 injections preceded the IL-22 injection by 15 minutes. Bothprotein injections were given by the intraperitoneal route. A bloodsample was taken from each mouse prior to treatment, then at 2 and 6hours after treatment. Serum was prepared from each of the samples formeasurement of SAA and IL-22.

An ELISA was performed as described previously to determine the level ofSAA in mice treated with IL-22 and a soluble receptor for IL-22,IL-22RA2-Fc4 described herein. Mice treated with 3 μg IL-22 inconjunction with IL-22RA2-Fc4 at concentrations between 20-100 ug showeda reduction in the level of SAA induced by IL-22 alone to backgroundlevels, demonstrating that IL-22RA2 inhibited the SAA induction activityof IL-22 in vivo.

EXAMPLE 8 Expression of IL-22 in Inflammatory Bowel Disease Mouse Model

Inflammatory Bowel disease (IBD) is a multifactorial disease, dividedinto two types, ulcerative colitis (UC) and Crohn's Disease (CD). Theetiology of these diseases is currently not known and clinicalmanifestations differ. UC is restricted to the colon, and symptomsinclude bloody diarrhea, weight loss and abdominal pain. Macroscopicfeatures of UC include punctuated ulcers and a shortened colon. Incontrast, Crohn's Disease can also affect other parts of the bowel.Symptoms include diarrhea (which is less often bloody than seen in UC),a low-grade fever and pain. Macroscopic features include fibrotic andstenotic bowel with strictures, deep ulcers, fissures and fistulas.

Several animal models are available that mimic these human diseases.Three commonly used models of colitis for new drug screening are the2,4,6-trinitrobenzene sulphonic acid (TNBS) induced rat model, the mouseT-cell transfer model, and the dextran sodium sulfate, or DSS-inducedmouse model. The DSS model was derived from a model by Dr. S. Murthy,using a disease activity index scoring system (S. N. S. Murthy,Treatment of Dextran Sulfate Sodium-Induced Murine Colitis byIntracolonic Cyclosiporin, Digestive Diseases and Sciences, Vol. 38, No.9 (September 1993), pp. 1722-1734).

In the present study, an acute colitis resulted when mice were fed DSSin their drinking water for 6 days. The animals exhibited weight lossand bloody diarrhea, mimicking the condition of UC patients. Themechanism of the DSS injury is not well characterized, but it is thoughtthat it induces a nonspecific inflammatory immune response and mimicsenvironmental effects on the bowel. It is possible that H₂S is produced,which could be toxic to cells. In addition, changes in luminal bacterialflora occur. Activated monocytes, macrophages and mast cells have beendemonstrated in the colon. Mediators for all three animal models includeinflammatory prostaglandins, leukotriene metabolites and cytokines.

A. Method

Colitis was induced by DSS ingestion in Swiss Webster female mice fromCharles River Laboratories. The mice were 10 and 11 weeks old at thestart of the study. Mice were given 4% DSS in the drinking water for aperiod of 6 days (treated mice), or were given only normal drinkingwater (control mice). A Disease Activity Index clinical score (DAI) wasused, which comprises a combination of measurements including stoolquality, occult blood and weight loss. DAI was obtained daily for eachmouse beginning one day after DSS treatment. After 6 days, DSS wasremoved from the drinking water of the treated mice. All mice weremonitored by DAI clinical score until sacrifice at either 2, 7 or 10days from the start of the study. On each of days 2 and 7, fourDSS-treated mice and one control mouse were sacrificed. On day 10, fourDSS-treated mice and two control mice were sacrificed. For all animalsafter sacrifice, the colon length was measured. Colon sections werefixed in 10% neutral buffered formalin for histologic analysis or frozenfor mRNA extraction.

B. Histologic Scoring and Disease Activity Index (DAI) Scoring

Histologic index scores were obtained following the method inreference 1. Generally, the colon sections were scored blinded by apathologist for crypt scores, hyperplastic epithelium, crypt distortionand inflammation.

Daily, each mouse was graded as to a clinical score based on weightloss, stool consistence and intestinal bleeding. Higher scores wereassigned for increasing amounts of weight loss, diarrhea and bleeding.The daily score for each mouse was the mean grade obtained from thethree results/observations.

C. Results

The colon lengths for DSS-treated mice were somewhat shorter on days 7and 10 than non-treated controls, but the results may not have beensignificant (not checked by a statistical application). The clinical DAIscores reflected a rise in disease symptoms in the DSS-treated micesimilar to that seen in past studies using this model. Occult blood wasgreatest on approximately days 4 and 5, while loose stools were moreprevalent on days 6 and 7. Histopathology results show that diseasescores were different from the controls on all sacrifice days,especially days 7 (peak) and 10. The histopathology screening scoreswere: controls=0.5, day 2 DSS-treated mice=8.8, day 7 DSS-treatedmice=21, day 10 DSS-treated mice=18. Clinical and histopathology scoresshow that the DSS-treated mice had significant colon disease relative tothe non-treated controls. The frozen tissue samples were used later formRNA determinations as described below.

D. Tissue Expression of IL-22 RNA in Murine IBD Colon Samples UsingRT-PCR:

To determine the relative expression of mouse IL-22 RNA (SEQ ID NO:10;SEQ ID NO:11) in an inflammatory bowel disease model, the distal colonsof DSS-treated mice were collected and snap frozen in liquid nitrogen.In this experiment mice were treated with DSS and samples were taken ondays 2, 7 and 10 post-treatment. Samples from normal untreated mice werecollected as well. RNA was then isolated from the samples using thestandard RNeasy Midiprep™ Kit (Qiagen, Valencia, Calif.) as permanufacturer's instructions.

The RT-PCR reactions used the ‘Superscript One-Step RT-PCR System withPlatinum Taq.’ (Life Technologies, Gaithersburg, Md.) Each 25 μlreaction consisted of the following: 12.5 μl of 2× Reaction Buffer, 0.5ul (20 pmol/μl) ZC39,289 (SEQ ID NO:17), 0.5 μl (20 pmol/ul) ZC39,290(SEQ ID NO:18), 0.4 μl RT/Taq polymerase mix, 10 ul RNase-free water,1.0 μl total RNA (100 ng/μl). The amplification was carried out asfollows: one cycle at 50° for 30 minutes followed by 35 cycles of 94°,30 seconds; 58°, 30 seconds; 72°, 60 seconds; then ended with a finalextension at 72° for 7 minutes. 8 to 10 μl of the PCR reaction productwas subjected to standard agarose gel electrophoresis using a 2% agarosegel. The correct predicted cDNA fragment size was observed as follows:There was a faint band in both day 2 samples. Two of three day 7 samplesgenerated a strong band while the third day 7 sample generated a verystrong band. The three day 10 samples generated a strong band. Finally,the two ‘normal’ control samples did not generate any band. Theseresults suggest that there may be an upregulation of IL-22 in certaintypes of inflammatory responses in the colon, including those associatedwith IBD, UC, and CD. The data is summarized in Table 7 below whereRelative Expression was scored as follows: 0=No band, 1=faint band,2=strong band, 3=very strong band.

TABLE 7 Tissue Relative Expression (0-3) Normal Colon 0 Normal Colon 0Day 2 Post Treatment 1 Day 2 Post Treatment 1 Day 7 Post Treatment 3 Day7 Post Treatment 2 Day 7 Post Treatment 2 Day 10 Post Treatment 2 Day 10Post Treatment 2 Day 10 Post Treatment 2

EXAMPLE 9 IL-22RA2 Decreases IL-6 and SAA Levels in Mouse CollagenInduced Arthritis (CIA) Model

A. Mouse Collagen Induced Arthritis (CIA) Model

Ten week old male DBA/1J mice (Jackson Labs) were divided into 3 groupsof 13 mice/group. On day-21, animals were given a subcutaneous injectionof 50-100 μl of 1 mg/ml chick Type II collagen formulated in CompleteFreund's Adjuvant (prepared by Chondrex, Redmond, Wash.), and threeweeks later on Day 0 they were given a 100 μl (25 μg) injection of LPSfrom E. coli 0111:B4, prepared as 250 μg/ml from a lyophilized aliquot(Sigma, St. Louis, Mo.). IL-22RA2 was administered as an intraperitonealinjection 3 times a week for 4 weeks, from Day 0 to Day 25. The firsttwo groups received either 100 or 10 μg of IL-22RA2 per animal per dose,and the third group received the vehicle control, PBS (LifeTechnologies, Rockville, Md.). Animals began to show symptoms ofarthritis following the LPS injection, with most animals developinginflammation within 2-3 weeks. The extent of disease was evaluated ineach paw by using a caliper to measure paw thickness, and by assigning aclinical score (0-3) to each paw: 0=Normal, 0.5=Toe(s) inflamed, 1=Mildpaw inflammation, 2=Moderate paw inflammation, and 3=Severe pawinflammation as detailed below.

A. Monitoring Disease:

Animals can begin to show signs of paw inflammation soon after thesecond collagen injection, and some animals may even begin to have signsof toe inflammation prior to the second collagen injection. Most animalsdevelop arthritis within 2-3 weeks of the boost injection, but some mayrequire a longer period of time. Incidence of disease in this model istypically 95-100%, and 0-2 non-responders (determined after 6 weeks ofobservation) are typically seen in a study using 40 animals. Note thatas inflammation begins, a common transient occurrence of variablelow-grade paw or toe inflammation can occur. For this reason, an animalis not considered to have established disease until marked, persistentpaw swelling has developed.

All animals were observed daily to assess the status of the disease intheir paws, which was done by assigning a qualitative clinical score toeach of the paws. Every day, each animal has its 4 paws scored accordingto its state of clinical disease. To determine the clinical score, thepaw can be thought of as having 3 zones, the toes, the paw itself (manusor pes), and the wrist or ankle joint. The extent and severity of theinflammation relative to these zones was noted including observation allthe toes for any joint swelling, torn nails, or redness, notation of anyevidence of edema or redness in any of the paws, and notation any lossof fine anatomic demarcation of tendons or bones, and evaluation thewrist or ankle for any edema or redness, and notation if theinflammation extends proximally up the leg. A paw a score of 1, 2, or 3was based first on the overall impression of severity, and second on howmany zones were involved. The scale used for clinical scoring is shownbelow.

Clinical Score:

0=Normal

0.5=One or more toes involved, but only the toes are inflamed

1=mild inflammation involving the paw (1 zone), and may include a toe ortoes

2=moderate inflammation in the paw & may include some of the toes and/orthe wrist/ankle (2 zones)

3=severe inflammation in the paw, wrist/ankle, and some or all of thetoes (3 zones)

Established disease is defined as a qualitative score of pawinflammation ranking 2 or more, that persists overnight (two days in arow). Once established disease is present, the date is recorded anddesignated as that animal's first day with “established disease”.

Blood was collected throughout the experiment to monitor serum levels ofanti-collagen antibodies. Animals were euthanized on Day 21, and bloodwas collected for serum and for CBC's. From each animal, one affectedpaw was collected in 10% NBF for histology and one was frozen in liquidnitrogen and stored at −80° C. for mRNA analysis. Also, ½ spleen, ½thymus, ½ mesenteric lymph node, one liver lobe and the left kidney werecollected in RNAlater for RNA analysis, and ½ spleen, ½ thymus, ½mesenteric lymph node, the remaining liver, and the right kidney werecollected in 10% NBF for histology. Serum was collected and frozen at−80° C. for immunoglobulin and cytokine assays.

No statistically significant differences were found between the groupswhen the paw scores and measurements data were analyzed, although therewas a suggestion that one treatment group receiving IL-22RA2 may havehad a delay in the onset and progression of paw inflammation. There wereno significant differences between the groups for changes in bodyweight, CBC parameters, or anti-collagen antibody levels. These earlyresults indicate that IL-22RA2 does not adversely effect body weight,red or white blood cells, or antibody production, but may be able toreduce inflammation. Further investigations into dosing, mechanism ofaction, and efficacy are under way (e.g., Example 10).

B. Anti-collagen ELISA Data in Mouse CIA Model

Serum samples were collected on days 0, 7, 14, 21 and 28 relative todate of LPS challenge (day 0) from the murine model of collagen inducedarthritis (Example 9A above). The serum samples were screened by ELISAfor anti-collagen antibody titers. There were no statisticallysignificant effects of IL-22RA2 treatment in 100 μg or 10 μg treatmentgroups on levels of anti-collagen antibodies compared with PBS controls.Below is a description of anti-collagen ELISA methods and materials.

Reagents used for anti-collagen ELISAs were Maxisorp 96-well microtiterplates (NUNC, Rochester, N.Y.), chick type-II collagen (Chondrex,Redmond, Wash.), Super Block (Pierce, Rockford, Ill.), horseradishperoxidase (HRP)-conjugated goat anti-mouse IgG+A+M (H+L) (Zymed, SouthSan Francisco, Calif.) and o-phenylenediamine dihydrochloride substrate(Pierce, Rockford, Ill.). Buffers used in all assays were ELISA Bdiluent buffer (PBS+0.1% BSA+0.05% Tween (Sigma, St. Louis, Mo.)), ELISAC wash buffer (PBS+0.05% Tween) and NovoD developing buffer (0.063Msodium citrate, 0.037M citric acid), H₂O₂ (Sigma) and 1N H₂SO₄ (VWR,Tukwilla, Wash.).

Approximately 100 μL of peripheral blood was collected by retro-orbitalbleed into serum separator tubes (Becton Dickinson). Serum was collectedby centrifugation (2-3 min, 16,000×g, 4-6° C.) and stored at −20° C.until analyzed. To determine anti-collagen Ig antibody levels, NUNCplates were coated with 10 μg/mL chick type-II collagen (Chondrex,Redmond Wash.) and incubated overnight at 4° C. Plates were washed withELISA C, blocked (5 minutes, room temperature) with Super Block (Pierce,Rockford, Ill.), and washed with ELISA C. Diluted serum samples (dilutedin ELISA B 5-fold from 1:5000 to 1:625,000) were added to ELISA platesin triplicate and the plates were incubated overnight at 4° C. Afterincubation, the plates were washed with ELISA C, and peroxidase-labeledgoat anti-mouse Ig Fc (Zymed, 1:2000 in ELISA B) was added. The plateswere incubated (room temperature, 90 minutes), rinsed again using ELISAC, and HRP activity was developed using o-phenylenediaminedihydrochloride substrate (10 mL NovoD+1 tablet OPD+10 μL H₂O₂, Pierce).The reaction was stopped with 1N H₂SO₄. Relative optical densitymeasurements of serum samples at 1:25,000 dilution were taken at 490 nmusing a Spectra MAX 190, and data were analyzed using SoftMax Prosoftware (Molecular Devices Corporation, Palo Alto, Calif.).

C. IL-6 and SAA Analysis in Mouse CIA Model

Day 0 serum samples were harvested from CIA mice (Example 9A above) 4 hrpost administration of 25 μg LPS intraperitoneally. Samples werescreened for IL-6 and serum amyloid A (SAA) concentrations by commercialELISA kits purchased for Biosource International (Camarillo, Calif.) asper manufacturer's instructions.

The IL-6 levels were 9651+/−1563 pg/ml, 10,865+/−1478 pg/ml and15,006+/−2,099 pg/ml in the mice groups subjected to 100 μg IL-22RA2, 10μg IL-22RA2 and PBS control, respectively. The IL-6 concentration in thegroup of CIA mice exposed to the 100 μg dose of IL-22RA2 wassignificantly lower compared to PBS control mice with p=0351.Statistical significance was calculated using Fisher's PLSD with asignificance level of 5% (ABACUS Concepts, INC, Berkeley, Calif.).

In addition, SAA concentrations were 381+/−40 μg/ml, 348+/−37 μg/ml and490+/−50 μg/ml in the mice groups subjected to 100 μg IL-22RA2, 10 μgIL-22RA2 and PBS control groups, respectively. The SAA concentration inthe group of CIA mice exposed to the 10 μg dose of IL-22RA2 wassignificantly lower compared with PBS control mice with p=0.0257.Statistical significance was calculated using Fisher's PLSD with asignificance level of 5% (ABACUS Concepts, INC, Berkeley, Calif.).

EXAMPLE 10 Anti-IL-22RA mAbs or Anti-IL-22 mAbs Inhibit Disease Severityin a Mouse CIA Model

The collagen-induced arthritis (CIA) model is a mouse model forrheumatoid arthritis that reflects to large extent the disease seen inhumans. (Moore, Methods Mol. Biol. 225:175-179, 2003: Waksman, Scand. J.Immunol., 56:12-34, 2002). Mice are immunized with 2 doses of collagenemulsified in CFA at the base of the tail. This results in swelling ofthe paws that increases over a period of time and can be both visuallyscored and measured using calipers. Furthermore, serum anti-collagenantibodies correlates well with severity of disease. Based on datashowing IL-20 and IL-22 induce inflammation, anti-IL-22RA and anti-IL-22mAbs are administered to groups of collagen-immunized mice, and effectson disease scores are evaluated. A decrease in paw scores and pawthickness after administration of anti-IL-22RA mAbs or anti-IL-22mAbs_suggests IL-20 and IL-22 promote ongoing immune response in a modelfor autoimmunity and blocking, inhibiting, reducing, antagonizing orneutralizing their function may inhibit autoimmune disorders. Inhibitionof serum TNFa and anti-collagen antibodies also suggests that blockingIL-22RA may be beneficial in autoimmune disease.

Thus, to determine if anti-IL-22RA mAbs or anti-IL-22 mAbs have aneffect on autoimmunity, they are tested in a mouse model for rheumatoidarthritis—collagen-induced arthritis (CIA). Specifically, DBA1J mice aregiven collagen injections to induce rheumatoid-like arthritis. Theinoculation on Day 0 is a subcutaneous injection of a homogenateconsisting of Complete Freund's Adjuvant (CFA) and Type II collagen(50-100 μl, prepared as 2 mg/ml of collagen). The injection is givennear the base of the tail. On Day 21, a second inoculation isadministered, the only difference being that the homogenate is preparedusing Incomplete Freund's Adjuvant (IFA), instead of the CFA. Paw scoresand thickness are measured daily. Groups of mice receive PBS, 20-200 ugcontrol isotype matched monoclonal antibody or 20-200 ug anti-IL-22RAmAb or anti-IL-22 mAb i.p 2× or 3×/week for 1-4 weeks starting at secondcollagen injection. Mice are monitored daily till day 30. Mice aresacrificed on day 30, serum taken for anti-collagen antibody analysisand serum cytokine analysis (TNF).

Inhibition of paw scores, paw thickness, serum TNFa and serumanti-collagen antibodies by administration of anti-IL-22RA or anti-IL-22mAbs suggests that blocking IL-22RA can bind, block, inhibit, reduce,antagonize or neutralize IL-22, and inhibit an ongoing immune responsein a model for autoimmunity and may inhibit autoimmune disorders.

EXAMPLE 11 Expression of IL-22 Receptor, IL-22RA, in the DSS Mouse Model

Quantitative RT-PCR was performed to measure expression levels of mouseIL-22RA in the colons of mice with DSS-induced IBD (Example 8). RNA wasisolated from normal mouse colon and from the distal colons ofDSS-treated mice from treatment days 2, 7 and 10. RT-PCR was performedusing Applied Biosystems 7700 TaqMan instrument and protocols. Briefly,“Primer Express” software was used to designed primers against the mouseIL-22RA sequence (ZC39776 (SEQ ID NO:19) and ZC39777 (SEQ ID NO:20)) anda FAM/TAMRA labeled TaqMan probe (ZC38752 (SEQ ID NO:21)) according toApplied Biosystems guidelines. 25 ng of RNA was added to each reaction,along with PE/Applied Biosystems TaqMan EZ RT-PCR Core Reagents and theabove mentioned primers and probe. RT-PCR reactions were run induplicate under the following conditions: 50° C. for 2 minutes, 60° C.for 30 minutes, 95° C. for 5 minutes, 40 cycles of 94° C. for 20 secondsand 60° C. for 1 minute. Expression values were compared to a standardcurve of known numbers of molecules of a synthetic mouse IL-22RA RNAtranscript, and expression is reported as absolute number of moleculesof mouse IL-22RA per reaction. Preliminary data suggests that mouseIL-22RA expression may be slightly down-regulated in the distal colonsof day 7 and day 10 mice with DSS-induced IBD when compared toexpression levels in normal mouse colon.

EXAMPLE 12 IL-22 and Proinflammatory Indicators in Mild EndotoxemiaModel: LPS-Induced Endotoxemia Mouse Model

A. LPS-Induced Endotoxemia Mouse Model: Assessment ProinflammatoryCytokines and Body Temperature in the LPS-Induced Endotoxemia MouseModel

An in vivo experiment was designed to examine the effect of IL-22RA2(IL-22RA2) in a mouse LPS model of mild endotoxemia. To initially assessthe model, we measured proinflammatory cytokines and body temperature tocollect reference data for the model.

Briefly, six month Balb/c (CRL) female mice were injected with 25 μg LPS(Sigma) in sterile PBS intraperitoneally (IP). Serum samples werecollected at 0, 1, 4, 8, 16, 24, 48 and 72 hr from groups of 8 mice foreach time point. Serum samples were assayed for inflammatory cytokinelevels. IL-1b, IL-6, TNFa, IL-10 and serum amyloid A protein (SAA)levels were measured using commercial ELISA kits purchased fromBiosource International (Camarillo, Calif.).

TNFa levels peaked to 4000 pg/ml and IL-10 levels were 341 pg/ml at 1 hrpost LPS injection. At 4 hr post LPS injection, IL-6, IL-1b and IL-10were 6,100 pg/ml, 299 pg/ml and 229 pg/ml, respectively. The SAA levelsin serum were 0.405 mg/ml by 4 hr post LPS injection. SAA concentrationsin serum continued to increase to 3.9 mg/ml by 24 hr post LPS, howeverSAA levels greater than 1 to 2 mg/ml in serum are difficult to measureaccurately or reproducibly with the existing ELISA kit due tointeractions between SAA and other serum components. These resultsindicated that proinflammatory cytokines, in addition to IL-22 (Example11B), were indeed produced in this model. Thus the following criteriawere established as biological markers for the LPS model of mildendotoxemia: TNFa serum levels 1 hr post LPS, IL-6 serum levels 4 hrpost LPS and SAA serum levels 4 and 8 hr post LPS.

Body temperatures in a separate group of animals were monitored bysurgically implanted telemetry devices over the course of the 72 hrexperiment. Body temperatures in mice dropped maximally by 2° C. from37.07° C. to 34.98° C. 30 minutes after LPS injection.

Injection of 100 ug IL-22RA2-Fc fusion protein 30 minutes prior to theLPS injection significantly reduced about 50% of the SAA induction at 4hr and 8 hr time point, while 10 ug IL-22RA2-Fc did not have significanteffect. There is no significant change to the TNF-alpha and IL-6 level.IL-22RA2-Fc injection reduced neutrophil count in circulation at 1 hrtime point. It showed the administration of IL-22RA2-Fc can neutralizeIL-22 activity in terms of SAA induction.

B. Detection of IL-22 Activity in Mouse Serum from LPS-InducedEndotoxemia Mouse Model Using BaF3/CRF2-4/IL-22RA Cells in an AlamarBlue Proliferation Assay

BaF3/CRF2-4/IL-22RA cells, described herein, were spun down and washedin PBS 2 times to ensure the removal of the mIL-3, and then spun a thirdtime and re-suspended in the complete media (RPMI 1640, 10% FBS, 1%GlutaMAX, 1% Sodium Pyruvate), but without mIL-3 (hereinafter referredto as “mIL-3 free media”). Cells were then counted in a hemocytometer.Cells were plated in a 96-well format at 5000 cells per well in a volumeof 100 μl per well using the mIL-3 free media.

Serum from the LPS-induced endotoxemia mice from the experimentdescribed in Example 11A above, was diluted to 2% in mIL-3 free media onthe top row of the plate and then diluted serially 1:2 down theremaining 7 rows on the 96-well plate, leaving a volume of 100 μl ineach well. This was then added to the 100 μl of cells, for final serumconcentrations of 1%, 0.5%, 0.25%, 0.125%, 0.063%, 0.031%, 0.016%, and0.018% in a total assay volume of 200 μl. The assay plates wereincubated at 37° C., 5% CO₂ for 4 days at which time Alamar Blue(Accumed, Chicago, Ill.) was added at 20 μl/well. Plates were againincubated at 37° C., 5% CO₂ for 16 hours. Alamar Blue gives afluourometric readout based on number of live cells, and is thus adirect measurement of cell proliferation in comparison to a negativecontrol. Plates were read on the Wallac Victor 2 1420 Multilabel Counter(Wallac, Turku, Finland) at wavelengths 530 (Excitation) and 590(Emmission).

Results showed no significant proliferation above background levels inthe 0 hour, 1 hour, 8 hour, and 16 hour time points. Serum samples fromthe 4 hour time point showed 4-fold to greater than 10-fold increases inproliferation above background, indicating the presence of IL-22 inthose samples.

C. LPS-Induced Endotoxemia Mouse Model: Experiment to Assess Effects ofIL-22RA2

The ability of IL-22RA2 treatment to effect proinflammatory indicatorsinduced with a single 25 μg LPS dose IP in mice was tested. All sampleswere analyzed for SAA, IL-22 and circulating neutrophil counts. Subsetsfrom each group were analyzed for particular cytokine levels (1 hoursamples were screened for TNF alpha, 4 hour samples were analyzed forIL-6). Animals were sacrificed at indicated time points in Table 8 belowand whole blood and serum were collected and aliquoted for analysis.

72 C57BL/6N female mice (CRL) were given a single IP dose of IL-22RA2 asdescribed in Table 8, below. Control mice were C57BL/6N (CRL).

30 minutes later, they received another IP injection of 25 μg LPS(Sigma) in 100 μl, to initiate an endotoxemia cascade. Mice in eachgroup were sacrificed at corresponding time points as indicated in Table8, 50 μl whole blood were collected to measure total numbers ofcirculating neutrophils and the rest were spun for serum and aliquotedfor various assays described herein.

TABLE 8 Group No Treatment LPS Sacrifice Samples A 8 100 μg IL-22RA2 IP25 μg IP 1 hour Serum aliquots 30 min post tx Blood for CBC B 8 10 μgIL-22RA2 IP 25 μg IP 1 hour Serum aliquots 30 min post tx Blood for CBCC 8 200 μl PBS IP 25 μg IP 1 hour Serum aliquots 30 min post tx Bloodfor CBC D 8 100 μg IL-22RA2 IP 25 μg IP 4 hours Serum aliquots 30 minpost tx Blood for CBC E 8 10 μg IL-22RA2 IP 25 μg IP 4 hours Serumaliquots 30 min post tx Blood for CBC F 8 200 μl PBS IP 25 μg IP 4 hoursSerum aliquots 30 min post tx Blood for CBC G 8 100 μg IL-22RA2 IP 25 μgIP 8 hours Serum aliquots 30 min post tx Blood for CBC H 8 10 μgIL-22RA2 IP 25 μg IP 8 hours Serum aliquots 30 min post tx Blood for CBCJ 8 200 μl PBS IP 25 μg IP 8 hours Serum aliquots 30 min post tx Bloodfor CBC K 5 controls none Pre LPS Serum aliquots Blood for CBCD. IL-22RA2-Fc4 Neutralizes SAA Induction In Vivo: SAA ELISA Showing SAAExpression Induced by LPS in LPS-Induced Endotoxemia Mouse Model isInhibited by IL-22RA2-Fc4 Injection:

To assess whether IL-22RA2 could inhibit the SAA induction in theLPS-induced endotoxemia mouse model, mice were injected with IL-22RA2,30 minutes prior to LPS injection, as shown in Table 8 in Example 11Cabove.

An ELISA to determine SAA levels in the 4 hour and 8 hour samples wasperformed using the Mouse SAA Immunoassay Kit (BioSource International,California) following the manufacturer's directions. At the 4 hour timepoint, mice treated with 100 μg or 10 μg of IL-22RA2 showed adose-dependant, statistically significant reduction in SAA levelsrelative to the PBS injected mice. At the 8 hour time point, micetreated with 100 μg, continued to show a statistically significantreduction in SAA levels relative to the PBS injected mice. Thisindicates that the presence of IL-22RA2 is able to inhibit the inductionof SAA by LPS in vivo.

EXAMPLE 13 In Vivo Effects of IL-22 Polypeptide on Skin

A. IL-22-Induced Acanthosis

Mice (female, C3H/HEJ, 8 weeks old; Jackson Labs, Bar Harbor, Me.) weredivided into three groups of six animals and one group of 4. HumanBHK-produced IL-22 was administered by constant infusion viamini-osmotic pumps, resulting in local and steady state serumconcentrations proportional to the concentration of the IL-22 containedin the pump. Alzet mini-osmotic pumps (model 2002; Alza corporation PaloAlto, Calif.) were loaded under sterile conditions with IL-22 protein(A601F, 0.22 mL) diluted in phosphate buffered saline (pH 7.0) to aconcentration within the pump of 2 mg/mL for group 1 mice, 0.2 mg/mL forgroup 2 mice, 0.02 mg/mL for group 3 mice, or 0 mg/mL (diluent only) forgroup 4 mice. Pumps were implanted subcutaneously in mice through a 1 cmincision in the dorsal skin, and the skin was closed with sterile woundclosures. These pumps are designed to deliver their contents at a rateof 0.5 μl per hour over a period of 14 days. Using this nominal rate ofinfusion, dose levels were calculated to be 24 μg/day, 2.4 μg/day, 0.24μg/day and 0 μg/day for groups 1-4, respectively.

At the end of the 14-day period, the mice were euthanized and anapproximately 1 cm square sample of skin surrounding the pump area wascollected from each mouse. The skin was fixed in 10% neutral bufferedformalin. Formalin fixed samples of skin were embedded in paraffin,routinely processed, sectioned at 5 um and stained with hematoxylin andeosin. The tissues were microscopically examined in blinded fashion byan ACVP board certified veterinary pathologist. Histological changeswere noted, and the severity of acanthosis (i.e. epidermal thickening)scored in a subjective manner using the following scoring system:0—normal, 1—minimal acanthosis, 2—mild acanthosis, 3—moderate acanthosisand 4—severe acanthosis. In addition, the skin of selected groups wasimaged with a CoolSnap digital camera (Roper Scientific, Inc., SanDiego, Calif.) and epidermal thickness measured using histomorphometrysoftware (Scion Image for Windows, v. 4.02, Scion Corp., Frederick,Md.).

Administration of IL-22 at 2.4, and 24 μg/day resulted in epidermalthickening as shown by the average acanthosis score (see s) consistentlygreater than observed in control group skin. Moreover, IL-22 treatedanimals also had mononuclear cell infiltrates in the epidermis. Theseinfiltrates were not observed in the vehicle treated controls.

Acanthosis scores of epidermal thickness and measurements of skinthickness (in generic units of pixels) by groups are shown in Table 9below, as follows:

TABLE 9 Average Measured Group # n = Pump Acanthosis Thickness 1 6   24μg IL-22/day 3.0 ND 2 6  2.4 μg IL-22/day 2.4 67.5 3 6 0.24 μg IL-22/day2.2 ND 4 4 PBS infusion 1.8 45.6B. Effect of IL-22RA2 on IL-22-Induced Acanthosis

Mice (female, C3H/HEJ, 8 weeks old; Jackson Labs, Bar Harbor, Me.) weredivided into eight groups of eight animals each. IL-22 was administeredby constant infusion via mini-osmotic pumps, as described in Example12A. Alzet mini-osmotic pumps (model 2001; Alza corporation Palo Alto,Calif.) were loaded under sterile conditions with IL-22 protein (A#601F,0.22 mL) diluted in phosphate buffered saline (pH 7.0) to aconcentration within the pump of 0.22 mg/mL for group 1-2 mice, 0.45mg/mL for group 3-4 mice, 0.9 mg/mL for group 5-6 mice, or 0 mg/mL(diluent only) for group 7-8 mice. These pumps are designed to delivertheir contents at a rate of 0.5 μl per hour over a period of 14 days.Using this nominal rate of infusion, dose levels were calculated to be10 μg/day in groups 1-2.5 μg/day on groups 3-4, 2.5 μg/day in groups 5-6and 0 μg/day for groups 7-8. For each pair of groups at a given doselevel of IL-22, one of the groups was injected three times (days 1, 3,and 5) with 0.1 mg of human IL-22RA2 Fc protein (described herein) bythe interperitoneal route. The other group was injected in the samefashion with vehicle (PBS).

On day 8 of the study, mice were euthanized and an approximately 1 cmsquare sample of skin surrounding the pump area was collected from eachmouse. The skin was fixed in 10% neutral buffered formalin. Formalinfixed samples of skin were embedded in paraffin, routinely processed,sectioned at 5 um and stained with hematoxylin and eosin. The tissueswere microscopically examined in blinded fashion by an ACVP boardcertified veterinary pathologist. This study was scored in a differentmanner than the previous example. The number of layers in the epidermis,from stratum basalis to stratum granulosum, was determined. Based on theresults, the sections were scored as follows: 0—normal (2-3 layers),1—mild thickening (3-4 layers), 2—moderate thickening (4-6 layers) and3—severe thickening (>6 layers).

Administration of IL-22 at 2.5, 5, 10 μg/day resulted in epidermalthickening (see Table 10). Moreover, IL-22 treated animals also hadmononuclear cell infiltrates in the epidermis. These infiltrates werenot observed in the vehicle treated controls. Concurrent administrationof 100 μg IL-22RA2 (3 injections) decreased the amount of epidermalthickening in mice treated with 5 μg IL-22/day.

Acanthosis scores of epidermal thickness by groups are shown in Table10, below, as follows:

TABLE 10 Group # n = Pump Injection Average Acanthosis 1 8 2.5 μgIL-22/day 100 μL vehicle (3 injections) 1.1 2 8 2.5 μg IL-22/day 100 μgIL-22RA2 (3 injections) 0.8 3 8   5 μg IL-22/day 100 μLvehicle (3injections) 2.0 4 8   5 μg IL-22/day 100 μg IL-22RA2 (3 injections) 0.65 8  10 μg IL-22/day 100 μL vehicle (3 injections) 2.0 6 8  10 μgIL-22/day 100 μg IL-22RA2 (3 injections) 1.9 7 8 Vehicle 100 μL vehicle(3 injections) 0.0 8 8 Vehicle 100 μg IL-22RA2 (3 injections) 0.0

Epidermal thickening and immune infiltrates were also observed in humanpsoriatic skins. The skin phenotype observed in IL-22 subcutaneousinjection further indicated the potential role of IL-22 in thepathogenesis of psoriasis. The fact that IL-22RA2-Fc can neutralize theIL-22 induced skin phenotype suggests the potential use of other IL-22antagonists such as and anti-IL-22 neutralizing antibody or solublereceptor for the treatment of psoriasis and other IL-22 inducedinflammatory diseases.

C. Effect of IL-22RA Soluble Receptors, and Anti-IL-22RA Antibodies onIL-22-Induced or IL-20-Induced Acanthosis

The activity of IL-22RA soluble receptors, or an antibody to IL-22RA, toinhibit the in vivo activity of IL-22 or IL-20 is evaluated in a similarmanner, using the histological endpoint of acanthosis caused bysubcutaneous infusion of IL-22 or IL-20 protein. In an example of thismodel C3H/HEJ mice are implanted with subcutaneous mini-osmotic pumps asdescribed in examples 12(A) and 12(B) above. During the period ofexposure to IL-22 or IL-20, the mice are treated by injection with thepurified monoclonal antibody to IL-22 or similarly injected with vehicleas control. At the end of the IL-22 infusion period, skin would besampled from the pump area for histological analysis. Similar to theIL-22RA2 soluble receptor IL-22 antagonist, IL-22 or IL-20 antagonistIL-22RA soluble receptors, or anti-IL-22RA antibodies of the presentinvention are expected to show reduction in epidermal thickening andimmune cell infiltrates caused by IL-22 or IL-20, and hence be useful asIL-22 or IL-20 antagonists as a therapeutic for psoriasis and otherIL-22 or IL-20 induced inflammatory disease.

EXAMPLE 14 IL-22 is Upregulated in Human Psoriatic Skin Samples

RNA Samples:

Normal skin samples as well as skin from psoriasis patients wereobtained. The latter included involved skin from stable plaque-typepsoriasis and from adjacent uninvolved skin. RNA was isolated from humanskin samples using conventional methods. The integrity and quality ofRNA samples was tested on the Agilent 2100 Bioanalyzer (AgilentTechnologies, Waldbronn Germany).

Primers and Probes for Quantitative RT-PCR

Real-time quantitative RT-PCR using the ABI PRISM 7700 SequenceDetection System (PE Applied Biosystems, Inc., Foster City, Calif.) hasbeen previously described (See, Heid, C. A. et al., Genome Research6:986-994, 1996; Gibson, U. E. M. et al., Genome Research 6:995-1001,1996; Sundaresan, S. et al., Endocrinology 139:4756-4764, 1998. Thismethod incorporates use of a gene specific probe containing bothreporter and quencher fluorescent dyes. When the probe is intact thereporter dye emission is negated due to the close proximity of thequencher dye. During PCR extension using additional gene-specificforward and reverse primers, the probe is cleaved by the 5′ to 3′nucleolytic activity of the rTth DNA Polymerase which releases thereporter dye from the probe resulting in an increase in fluorescentemission.

The primers and probes used for real-time quantitative RT-PCR analysesof IL-22 expression were designed using the primer design softwarePRIMER EXPRESS™ (PE Applied Biosystems, Foster City, Calif.). Primersfor human IL-22 were designed spanning an intron-exon junction toeliminate amplification of genomic DNA. The forward primer, ZC42459 (SEQID NO:22) and the reverse primer, ZC42458 (SEQ ID NO:23) were used in aPCR reaction (below) at a 800 nM concentration to synthesize a 72 bpproduct. The corresponding IL-22 probe, ZC42460 (SEQ ID NO:24) wassynthesized and labeled in house at ZymoGenetics. The IL-22 probe waslabeled at the 5′ end with a reporter fluorescent dye(6-carboxy-fluorescein) (FAM) (PE Applied Biosystems) and at the 3′ endwith a quencher fluorescent dye (6-carboxy-tetramethyl-rhodamine)(TAMRA) (PE Applied Biosystems).

C. Real-time Quantitative RT-PCR

Relative levels of IL-22 mRNA were determined by analyzing total RNAsamples using the TaqMan EZ RT-PCR Core Reagents Kit (PE AppliedBiosystems). Runoff IL-22 transcript was made to generate a standardcurve used for quantitation. The curve consisted of 10-fold serialdilutions ranging from about 1e8 to 1e3 total copies of whole messagefor IL-22 with each standard curve point analyzed in triplicate. Thetotal RNA samples from skin were also analyzed in triplicate for humanIL-22 transcript levels and for levels of hGUS as an endogenous control.In a total volume of 25 μl, each RNA sample was subjected to TaqMan EZRT-PCR reaction (PE Applied Biosystems) containing: approximately 25 ngof total RNA in DEPC treated water (Dnase/Rnase free); appropriateprimers (approximately 800 nM ZC 42459 (SEQ ID NO:22) and ZC 42458 (SEQID NO:23); appropriate probe (approximately 100 nM ZC 42460 (SEQ IDNO:24); 1×TaqMan EZ Buffer; 3 mM Manganese acetate; 300 μM each d-CTP,d-ATP, and d-GTP and 600 μM of d-UTP; rTth DNA Polymerase (0.1 U/μl);and AmpErase UNG (0.01 U/μl). PCR thermal cycling conditions were asfollows: an initial UNG treatment step of one cycle at 50° C. for 2minutes; followed by a reverse transcription (RT) step of one cycle at60° C. for 30 minutes; followed by a deactivation of UNG step of onecycle at 95° C. for 5 minutes; followed by 40 cycles of amplification at94° C. for 20 seconds and 60° C. for 1 minute.

Relative IL-22 RNA levels were determined by using the Standard CurveMethod as described by the manufacturer, PE Biosystems (User Bulletin#2: ABI Prism 7700 Sequence Detection System, Relative Quantitation ofGene Expression, Dec. 11, 1997). The hGUS measurements were used tonormalize the IL-22 levels. Data are shown in Table 11 below.

TABLE 11 Skin Sample IL-22 Normal 0 Uninvolved 0 Involved 1149

IL-22 mRNA was undetectable in skin samples from normal patients or fromuninvolved areas. In contrast, there was dramatic upregulation for IL-22message in involved skin from psoriasis patients. These data support astrong disease association for IL-22 to human psoriasis.

Over expression of IL-22 was shown in human psoriatic lesions,suggesting that IL-22 is involved in human psoriasis. Moreover, asdescribed herein, over expression of IL-22 in transgenic mice showedepidermal thickening and immune cell involvement indicative of apsoriatic phenotype, and in addition injection of IL-22 into normal miceshowed epidermal thickening and immune cell involvement indicative of apsoriatic phenotype which was ablated by the soluble receptor antagonistIL-22RA2. Such in vivo data further suggests that the pro-inflammatoryIL-22 is involved in psoriasis. As such, antagonists to IL-22 activity,such as the anti-human-IL-22 monoclonal antibodies of the presentinvention, as well as soluble receptors and antibodies thereto, areuseful in therapeutic treatment of inflammatory diseases, particularlyas antagonists to IL-22 in the treatment of psoriasis. Moreover,antagonists to IL-22 activity, such as the anti-human-IL-22 monoclonalantibodies of the present invention, as well as soluble receptors andantibodies thereto, are useful in therapeutic treatment of otherinflammatory diseases for example as antagonists to IL-22 in thetreatment of atopic dermatitis, IBD, colitis, Endotoxemia, arthritis,rheumatoid arthritis, and psoriatic arthritis, adult respiratory disease(ARD), septic shock, multiple organ failure, inflammatory lung injurysuch as asthma or bronchitis, bacterial pneumonia, psoriasis, eczema,atopic and contact dermatitis, and inflammatory bowel disease such asulcerative colitis and Crohn's disease.

EXAMPLE 15 IL-22 is Upregulated in Human Atopic Dermatitis Skin Samples

Normal skin samples (n=4) as well as skin from atopic dermatitispatients (n=4) were obtained. RNA was isolated from human skin samplesusing conventional methods. The integrity and quality of RNA samples wastested on the Agilent 2100 Bioanalyzer (Agilent Technologies, WaldbronnGermany).

Primers and Probes for Quantitative RT-PCR

Real-time quantitative RT-PCR using the ABI PRISM 7700 SequenceDetection System (PE Applied Biosystems, Inc., Foster City, Calif.) hasbeen previously described (See, Heid, C. A. et al., Genome Research6:986-994, 1996; Gibson, U. E. M. et al., Genome Research 6:995-1001,1996; Sundaresan, S. et al., Endocrinology 139:4756-4764, 1998. Thismethod incorporates use of a gene specific probe containing bothreporter and quencher fluorescent dyes. When the probe is intact thereporter dye emission is negated due to the close proximity of thequencher dye. During PCR extension using additional gene-specificforward and reverse primers, the probe is cleaved by the 5′ to 3′nucleolytic activity of the rTth DNA Polymerase which releases thereporter dye from the probe resulting in an increase in fluorescentemission.

The primers and probes used for real-time quantitative RT-PCR analysesof IL-22 expression were designed using the primer design softwarePRIMER EXPRESS™ (PE Applied Biosystems, Foster City, Calif.). Primersfor human IL-22 were designed spanning an intron-exon junction toeliminate amplification of genomic DNA. The forward primer, ZC42459 (SEQID NO:22) and the reverse primer, ZC42458 (SEQ ID NO:23) were used in aPCR reaction (below) at a 800 nM concentration to synthesize a 72 bpproduct. The corresponding IL-22 probe, ZC42460 (SEQ ID NO:24) wassynthesized and labeled in house at ZymoGenetics. The IL-22 probe waslabeled at the 5′ end with a reporter fluorescent dye(6-carboxy-fluorescein) (FAM) (PE Applied Biosystems) and at the 3′ endwith a quencher fluorescent dye (6-carboxy-tetramethyl-rhodamine)(TAMRA) (PE Applied Biosystems).

C. Real-time Quantitative RT-PCR

Relative levels of IL-22 mRNA were determined by analyzing total RNAsamples using the TaqMan EZ RT-PCR Core Reagents Kit (PE AppliedBiosystems). Runoff IL-22 transcript was made to generate a standardcurve used for quantitation. The curve consisted of 10-fold serialdilutions ranging from about 1e8 to 1e3 total copies of whole messagefor IL-22 with each standard curve point analyzed in triplicate. Thetotal RNA samples from skin were also analyzed in triplicate for humanIL-22 transcript levels and for levels of hGUS as an endogenous control.In a total volume of 25 μl, each RNA sample was subjected to TaqMan EZRT-PCR reaction (PE Applied Biosystems) containing: approximately 25 ngof total RNA in DEPC treated water (Dnase/Rnase free); appropriateprimers (approximately 800 nM ZC 42459 (SEQ ID NO:22) and ZC 42458 (SEQID NO:23); appropriate probe (approximately 100 nM ZC 42460 (SEQ IDNO:24); 1×TaqMan EZ Buffer; 3 mM Manganese acetate; 300 μM each d-CTP,d-ATP, and d-GTP and 600 μM of d-UTP; rTth DNA Polymerase (0.1 U/μl);and AmpErase UNG (0.01 U/μl). PCR thermal cycling conditions were asfollows: an initial UNG treatment step of one cycle at 50° C. for 2minutes; followed by a reverse transcription (RT) step of one cycle at60° C. for 30 minutes; followed by a deactivation of UNG step of onecycle at 95° C. for 5 minutes; followed by 40 cycles of amplification at94° C. for 20 seconds and 60° C. for 1 minute.

Relative IL-22 RNA levels were determined by using the Standard CurveMethod as described by the manufacturer, PE Biosystems (User Bulletin#2: ABI Prism 7700 Sequence Detection System, Relative Quantitation ofGene Expression, Dec. 11, 1997). The hGUS measurements were used tonormalize the IL-22 levels.

IL-22 mRNA was undetectable in skin samples from normal patients. Incontrast, there was dramatic upregulation for IL-22 message in 3 out of4 skin samples from atopic dermatitis patients (about 400-2300 copies).These data support a strong disease association for IL-22 to humanatopic dermatitis.

Over expression of IL-22 was shown in human atopic dermatitis skins,suggesting that IL-22 is involved in human atopic dermatitis. Moreover,as described herein, over expression of IL-22 in transgenic mice showedepidermal thickening and immune cell involvement indicative of an atopicdermatitis phenotype, and in addition injection of IL-22 into normalmice showed epidermal thickening and immune cell involvement indicativeof a atopic dermatitis phenotype which was ablated by the solublereceptor antagonist IL-22RA2. Such in vivo data further suggests thatthe pro-inflammatory IL-22 is involved in atopic dermatitis. As such,antagonists to IL-22 activity, such as the anti-human-IL-22 monoclonalantibodies of the present invention, as well as soluble receptors andantibodies thereto, are useful in therapeutic treatment of inflammatorydiseases, particularly as antagonists to IL-22 in the treatment ofatopic dermatitis. Moreover, antagonists to IL-22 activity, such as theanti-human-IL-22 monoclonal antibodies of the present invention, as wellas soluble receptors and antibodies thereto, are useful in therapeutictreatment of other inflammatory diseases for example as antagonists toIL-22 in the treatment of atopic dermatitis, IBD, colitis, Endotoxemia,arthritis, rheumatoid arthritis, and psoriatic arthritis, adultrespiratory disease (ARD), septic shock, multiple organ failure,inflammatory lung injury such as asthma or bronchitis, bacterialpneumonia, atopic dermatitis, eczema, atopic and contact dermatitis, andinflammatory bowel disease such as ulcerative colitis and Crohn'sdisease.

EXAMPLE 16 Human IL-22 Polyclonal Antibodies

Anti IL-22 Polyclonal antibodies were prepared by immunizing 2 femaleNew Zealand white rabbits with the purified mature recombinant humanIL-22 polypeptide (amino acid residues 22 (Ala) to 167 (Ile) of SEQ IDNO:6), produced from BHK cells (IL-22-BHK). The rabbits were each givenan initial intraperitoneal (ip) injection of 200 μg of purified proteinin Complete Freund's Adjuvant followed by booster IP injections of 100μg peptide in Incomplete Freund's Adjuvant every three weeks. Seven toten days after the administration of the second booster injection (3total injections), the animals were bled and the serum was collected.The animals were then boosted and bled every three weeks.

The human IL-22-specific polyclonal antibodies were affinity purifiedfrom the immune rabbit serum using a CNBr-SEPHAROSE 4B protein column(Pharmacia LKB) that was prepared using 10 mg of the specific antigenpurified recombinant protein human IL-22-BHK per gram of CNBr-SEPHAROSE,followed by 20× dialysis in PBS overnight. Human IL-22-specificantibodies were characterized by ELISA using 500 ng/ml of the purifiedrecombinant protein human IL-22-BHK as antibody target. The lower limitof detection (LLD) of the rabbit anti-human IL-22 affinity purifiedantibody is 280 pg/ml on its specific purified recombinant antigen humanIL-22-BHK.

The human IL-22-specific polyclonal antibodies were characterizedfurther for their ability to block the cell-proliferative activity(“neutralization assay”) of purified recombinant human IL-22-BHK onBaF3/CRF2-4/IL-22RA cells (Example 2 and Example 3). A 50× molar excessof the human IL-22-specific polyclonal antibodies was sufficient toinhibit cell proliferation.

EXAMPLE 17 Anti-human IL-22 Monoclonal Antibodies

Monoclonal antibodies were prepared by immunizing 4 femaleSprague-Dawley Rats (Charles River Laboratories, Wilmington, Mass.),with the purified mature recombinant human IL-22 polypeptide (amino acidresidues 22 (Ala) to 167 (Ile) of SEQ ID NO:6), produced from BHK cells(IL-22-BHK). The rats were each given an initial intraperitoneal (IP)injection of 100 μg of the purified human recombinant IL-22 protein inComplete Freund's Adjuvant (Pierce, Rockford, Ill.) followed by boosterIP injections of 50 μg of the purified recombinant protein in IncompleteFreund's Adjuvant every two weeks. Seven to ten days after theadministration of the third booster injection, the animals were bled andthe serum was collected.

The human IL-22-specific rat sera samples were characterized by ELISAusing 500 ng/ml biotinylated human IL-22-BHK and 500 ng/ml biotinylatedmouse IL-22, biotinylated muIL-22-E. coli (R+D Systems, Minneapolis,Minn.) antibody targets. Three rat serum samples had titer to thespecific antibody target biotinylated human IL-22-BHK at a dilution of1:1E5 and to the specific antibody target biotinylated muIL-22-E. coliat a dilution of 1:1 E4.

Splenocytes and lymphatic node cells were harvested from 2 high-titerrats and fused to SP2/0 (mouse) myeloma cells using PEG 1500 in twoseparate fusion procedures (4:1 fusion ratio, splenocytes to myelomacells, “Antibodies A Laboratory Manual, E. Harlow and D. Lane, ColdSpring Harbor Press). Following 10 days growth post-fusion, specificantibody-producing hybridoma pools were identified by ELISA using thebiotinylated recombinant protein human IL-22-BHK and the biotinylatedrecombinant protein muIL-22-E. coli as separate antibody targets.Hybridoma pools positive in both ELISA protocols were analyzed furtherfor their ability to block or reduce the cell-proliferative activity(“neutralization assay”) of purified recombinant muIL-22-E. coli onBaF3/CRF2-4/IL-22RA cells (Example 2 and Example 3).

Hybridoma pools yielding positive results by ELISA only or ELISA and the“neutralization assay” were cloned at least two times by limitingdilution.

Monoclonal antibodies purified from tissue culture media werecharacterized for their utility in an ELISA for the quantitativedetermination of recombinant and native human IL-22 in mouse and humanserum samples. The two antibodies selected resulted in a quantitativeassay with a lower limit of detection of approximately 1 ng/mlrecombinant huIL-22-E. coli in 100% human serum.

Monoclonal antibodies purified from tissue culture media werecharacterized for their ability to block or reduce thecell-proliferative activity (“neutralization assay”) of purifiedrecombinant huIL-22-E. coli or muIL-22-E. coli on BaF3/CRF2-4/IL-22RAcells (Example 2 and Example 3). Six “neutralizing” monoclonalantibodies were identified in this manner. Hybridomas expressing theneutralizing monoclonal antibodies to human IL-22 described above weredeposited with the American Type Tissue Culture Collection (ATCC;Manassas Va.) patent depository as original deposits under the BudapestTreaty and were given the following ATCC Accession Nos.: clone266.16.1.4.4.1 (ATCC Patent Deposit Designation PTA-5035); clone266.5.1.2.2.3 (ATCC Patent Deposit Designation PTA-5033); clone267.17.1.1.4.1 (ATCC Patent Deposit Designation PTA-5038); clone267.4.1.1.4.1 (ATCC Patent Deposit Designation PTA-5037); clone266.12.6.1.3.2.1 (ATCC Patent Deposit Designation PTA-5034); clone266.19.1.10.5.2 (ATCC Patent Deposit Designation PTA-5036); and clone267.9.1.1.4.1 (ATCC Patent Deposit Designation PTA-5353).

EXAMPLE 18 Anti-IL-22RA Monoclonal Antibodies

Monoclonal antibodies were prepared by immunizing 4 Lewis Rats (RocklandImmunochemicals, Gilbertsville, Pa.), with the cleaved and purifiedrecombinant fusion protein, muIL-22RA-Fc (SEQ ID NO:4). The rats wereeach given an initial intraperitoneal (IP) injection of 100 μg of thepurified recombinant fusion protein in Complete Freund's Adjuvant(Pierce, Rockford, Ill.) followed by booster IP injections of 50 μg ofthe purified recombinant protein in Incomplete Freund's Adjuvant everytwo weeks for four weeks. Following the first four weeks ofimmunizations, booster IP injections of 50 ug of the cleaved purifiedrecombinant protein coupled to the carrier protein keyhole limpethemocyanin (KLH, Pierce, Rockford, Ill.) in Incomplete Freund's wereadministered every two weeks for four weeks. Seven to ten days after theadministration of the fourth booster injection, the animals were bledand the serum was collected.

The muIL-22RA-specific rat serum samples were characterized by ELISAusing 500 ng/ml of the purified recombinant fusion protein muIL-22RA-Fcas the specific antibody target and an unrelated fusion protein as anon-specific antibody target.

Splenocytes were harvested from one high-titer rat and fused to SP2/0(mouse) myeloma cells in an optimized PEG-mediated fusion protocol(Rockland Immunochemicals). Following 12 days growth post-fusion,specific antibody-producing hybridoma pools were identified by ELISAusing 500 ng/ml each of the purified recombinant fusion proteinmuIL-22RA-Fc-Bv as the specific antibody target and an unrelated fusionprotein as a non-specific antibody target. Hybridoma pools positive tothe specific antibody target only were analyzed further for theirability to block or reduce the cell-proliferative activity(“neutralization assay”) of purified recombinant muIL-22-E. coli onBaF3/CRF2-4/IL-22RA cells (Example 2 and Example 3) and an ability tobind via FACS analysis to BaF3/CRF2-4/IL-22RA cells (Example 2 andExample 3) as antibody target.

Hybridoma pools yielding a specific positive result in the ELISA assayand positive results in either the FACS or “neutralization assay” werecloned at least two times by limiting dilution.

Monoclonal antibodies in tissue culture media were characterized fortheir ability to block or reduce proliferation of BaF3/CRF2-4/IL-22RAcells (Example 2 and Example 3), grown in the presence of the purifiedrecombinant proteins muIL-22-E. coli or huIL-22-BHK. Fourteen“neutralizing” monoclonal antibodies have been identified and ninemonoclonal antibodies have been cloned.

Hybridomas expressing the neutralizing monoclonal antibodies to mouseIL-22RA described above were deposited with the American Type TissueCulture Collection (ATCC; Manassas Va.) patent depository as originaldeposits under the Budapest Treaty and were given the following ATCCAccession Nos.: clone R2.1.1G11.1 (ATCC Patent Deposit Designation[PTA-6035]); clone R2.1.5F4.1 (ATCC Patent Deposit Designation[PTA-6024]); clone R2.1.5H8.1 (ATCC Patent Deposit Designation[PTA-6025]); clone R2.1.12G7.1 (ATCC Patent Deposit Designation[PTA-6036]); clone R2.1.13C8.1 (ATCC Patent Deposit DesignationPTA-5037); clone R2.1.15E2.1 (ATCC Patent Deposit Designation[PTA-6038]); clone R2.1.16C11.1 (ATCC Patent Deposit Designation[PTA-6039]); clone R2.1.18C8.1 (ATCC Patent Deposit Designation[PTA-6048]); and clone R2.1.21G8.2(ATCC Patent Deposit DepositDesignation [PTA-6111]).

Hybridomas expressing the neutralizing monoclonal antibodies to humanIL-22RA will be deposited with the American Type Tissue CultureCollection (ATCC; Manassas Va.) patent depository as original depositsunder the Budapest Treaty and have been given the following ATCCAccession Nos.: 280.46.3.4 (ATCC Patent Deposit Designation PTA-6284);clone 281.73.49.1.1 (ATCC Patent Deposit Designation PTA-6285); clone283.4.1.2 (ATCC Patent Deposit Designation PTA-6287); clone 283.52.5.4(ATCC Patent Deposit Designation PTA-6311); and clone 283.108.2.3 (ATCCPatent Deposit Designation PTA-6286).

EXAMPLE 19 Binding Affinity of Two Rat-anti-Ms-IL-22RA MAb

Goat-anti-Rat IgG-Fc gamma specific Antibody (Jackson) was immobilizedonto a CM5 Biacore chip. The assay was optimized to bind each mAb ontothe anti-Rat capture surface and then a concentration series of IL-22RAwas injected across the mAb to see association (Ka) and dissociation(Kd). After preliminary testing, non-specific binding was observedbetween the fusion protein and the capture surface on the chip. A vialof IL-22RA that had the Fc4 tag cleaved by thrombin was acquired andsubsequently tested to show no background effects. After each run, thesurface was regenerated back to the anti-Rat Antibody with 2 injectionsof 20 mM HCl. Data was generated for each MAb and evaluation software(BIAevaluation software version 3.2, Pharmacia BIAcore, Uppsala, Sweden)was used to assess the kinetics of the anti-IL-22RA antibody binding tothe IL-22RA protein, as shown in Table 12 below

TABLE 12 Clone R2.1.5F4.1** Clone R2.1.15E2.1** ka (M−1s−1) 1.49E+06 ka(M−1s−1) 1.76E+06 kd (s−1) 1.70E−04 kd (s−1) 2.55E−04 KA (M−1) 8.76E+09KA (M−1) 6.66E+09 KD (M) 1.14E−10 KD (M) 1.504E−10  Chi2 2.08 Chi2 1.5**Equilibrium association (K_(a)) and dissociation (K_(d)) rateconstants for each anti IL-22RA MAB are shown and values fall in machinelimits. Chi2 refers to the sum of the square of the residuals betweenthe binding curves and the evaluation fitting curves. The closer the 0,the more confidence in the data.

As shown by Table 12, both anti-IL-22RA MAb's bind strongly to theIL-22RA protein, as evinced by the binding in pico-molar concentrationto the IL-22RA (thrombin-cleaved Fc4 tag). This data is shown with goodconfidence based on the low Chi² values and shows mAb Clone R2.1.5F4.1to have a slightly stronger affinity for the IL-22RA receptor.

EXAMPLE 20 Immunohistochemical Analysis of IL-22 Protein Expression InVivo in Tissue Samples

A. Summary

Immunohistochemical (IHC) analysis of IL-22 protein expression andlocalization was achieved using anti-human IL-22 (anti-hIL-22)monoclonal antibody (Mab 266.19.1.10.5.2) in the following tissuesamples: a Human multi-Normal Grid and Tumor Grid; Human pancreatitis,lung and renal disease samples; Human psoriasis skin samples; INS IL-22TG (expressed from the rat insulin promoter) and WT mouse pancreas;muIL-22-EuLCK TG and WT mouse skin sample; and DSS (WT and IL-22 KO)mouse colon sample. Moreover the staining pattern of anti-hIL-22monoclonal antibody MAB 266.19.1.10.5.2 (Example 17) vs. polyclonalantibody (rabbit anti-hIL-22) (Example 16) was compared.

The rat anti-Human IL-22 monoclonal antibodies MAb 266.16.1.4.4.1, andMAb 266.19.1.10.5.2 (Example 17) were tested were shown to stain themajority of BHK/human IL-22 (>50%) but also some BHK/mouse IL-22 cells(1-5%), and were used to investigate the tissue distribution andexpression of IL-22 in both human patient and animal model samples andused to compare the staining pattern with polyclonal rabbit antibody toconfirm the results.

B. Materials and Methods

Formalin-fixed and paraffin-embedded cells and tissues from humansources and mouse animal models were sectioned at 5 μm. The cellsincluded BHK cells expressing either human or mouse IL-22 and wild typeas positive control and negative control, respectively. The humantissues included a Multi-tissue control slide (NORMALGRID™; Biomeda,Foster City, Calif.) with 50 sections of various normal human tissues(e.g., brain, pituitary gland, adrenal gland, breast, kidney, heart,stomach, small intestine, large intestine, fetal liver, liver, skin,pancreas, lung, tonsil, ovary, testis, prostate, uterus, placenta,thyroid and spleen); a Multi-tissue control slide (TUMORGRID™; Biomeda,Foster City, Calif.) with 50 sections of various human tumors (e.g.,lung adeno Ca., liver adeno Ca., kidney adeno Ca., colon adeno Ca.,breast adeno Ca., thyroid adeno Ca., stomach adeno Ca., prostate adenoCa., pancreas adeno Ca., ovary adeno Ca., lymphoma, melanoma, sarcomaewings, sarcoma epithelioid, sarcoma MFH, sarcoma Rhabdo, carcinoid,undiff. Ca., mesothelioma, teretoma and seminoma); lung carcinoma fromCHTN (Cooperation Human Tissue Network, Cleveland, Ohio); normalpancreas, pancreas with chronic pancreatitis, lung with chronicperivascular inflammation, kidneys with either multifocalglomerulosclerosis, mesangioproliferative glomerulonephritis, orsclerotic glomeruli interstitial fibrosis from NDRI (National DiseaseResearch Interchange, Philadelphia, Pa.); and psoriatic skin samplesfrom human. The mouse tissues included colons from inflammatory boweldisease animal model (DSS model disclosed herein, Swiss Webster femalemice) and from IL-20 WT and KO colitis animal model (DSS mice, wild typeand IL-20 (IL-20) knock out female mice) treated with either vehicle or4% DSS in drinking water for 7 days; and skin samples from transgenic(TG) animal models including mIL-22-EuLCK TG and mIL-22-INS control andTG animals. One section per block/slide was stained with hematoxylin andeosin (H&E) for histologic examination and the subsequent section wereimmunohistochemically stained for IL-22 protein expression andlocalization.

For immunohistochemistry, the cell and tissue sections were placed onCHEMMATE™ Capillary Gap Plus microscope slides (BioTek, Winooski, Vt.),dried at 60° C. oven for 60 minutes and dewaxed using standardconditions of 3×5 minutes in xylene, 4 minutes in 100% EtOH, 3 minutesin 100% EtOH, and 2 minutes in 95% EtOH. The tissue sections were thensubjected to a 20-minute enzyme-induced epitope retrieval process at 37°C. with pepsin (NeoMarkers Fremont Calif.) followed by anavidin/biotin-blocking step done according to the manufacturersinstructions (Zymed, South San Francisco, Calif.). TECHMATE 500™Automated Immunostainer and Immunoperoxidase (IP) immunohistochemicalprotocol with avidin-biotin-complex detection system (Ventana BiotekSystems, Tucson, Ariz.) were employed for the staining. The TECHMATE500™ Automated Immunostainer employed the principle of capillary actionand the IP protocol utilized a type of immunostaining referred to as a“sandwich” technique. The sections were preblocked with 5% normal goatserum (Vector, Burlingame Calif.) in PBS for 10 minutes followed by 1×buffer1 wash (Signet, Dedham Mass.) and then incubated with a primaryantibody against IL-22 (MAB 266.19.1.10.5.2) (Example 17), PAS purifiedat 2.04 mg/ml) diluted at 1:800 for 30 minutes at room temperaturefollowed by 5× buffer1 wash. The primary antibody was diluted inTECHMATE 500™ antibody dilution buffer (Ventana). Biotinylated goatanti-rat IgG (Vector) diluted at 1:200 plus 5% normal goat serum and2.5% nonfat dry milk in PBS was used as the secondary-linking antibodiesfor 25 minutes at room temperature followed by 1× buffer1 wash and 1×Buffer2&3 wash (Signet). The tissues sections were then subjected to a3×7 minutes 3% hydrogen peroxide (HP) blocking (Ventana) followed by 3×buffer2&3 wash. Immunoperoxidase labeling was performed with a peroxidesDAB kit (Ventana), incubating with avidin-biotin-complex (ABC) for 30minutes followed by 5× buffer2&3 wash and diaminobenzidine (DAB) for 4×4minutes followed by 2× buffer2&3 wash and 1× water wash (Signet, Cat.No. 2340). Tissues were then counter stained with methyl green (Dako,Cat. No. S1962) for 10 minutes followed by 2× buffer2&3 wash and 3×water wash. Control included non-immune primary sera using rat primaryantibody isotype control (Zymed) to replace the primary antibody.

Immunostaining was observed using an Olympus BH-2 microscope and imageswere captured by CoolSNAP HQ digital camera (Roper Scientific, Tucson,Ariz.).

C. Results

Positive and negative control cell lines: MAB 266.19.1.10.5.2, ananti-hIL-22 monoclonal antibody, demonstrated positive staining on bothhuman IL-22 expressing BHK cells (+++) and murine IL-22 expressing BHKcells (+), and no staining on the wild type BHK cells (−). All thepositive and negative BHK cell lines stained with rat isotype negativecontrol to replace the primary antibody showed no staining (−) whichindicated that the antibody is specific to IL-22 ligand. The antibodyhad cross immunoreactivity to both human and mouse IL-22.

Human tissues: Human multi-Normal Grid and Tumor Grid; pancreas, lungand renal disease samples; and human psoriasis skin samples wereexamined. These human tissues included 1). Brain, pituitary gland,adrenal gland, breast, kidney, heart, stomach, small intestine, largeintestine, fetal liver, liver, skin, pancreas, lung, tonsil, ovary,uterus, testis, placenta, thyroid and spleen on the Multi-tissue controlslides (NORMALGRID™)/normal human tissues; 2). Lung adeno Ca., liveradeno Ca., kidney adeno Ca., thyroid adeno Ca., stomach adeno Ca.,prostate adeno Ca., pancreas adeno Ca., ovary adeno Ca., lymphoma,melanoma, sarcoma ewings, sarcoma epithelioid, sarcoma MFH, sarcomaRhabdo, carcinoid, undiff. Ca., mesothelioma, teratoma, and seminoma, onthe Multi-tissue control slides (TUMORGRID™)/human abnormaltissues/tumor; 3). Normal pancreas, pancreas with chronic pancreatitis,lung with chronic perivascular inflammation, lung Ca., kidney withmultifocal glomerulosclerosis, kidney with mesangioproliferativeglomerulonephritis, kidney with sclerotic glomeruli interstitialfibrosis from CHTN and/or NDRI; 4).

Mouse tissues: INS IL-22 TG and WT mouse pancreas were examined.Scattered cells throughout the islets in the INS IL-22 TG pancreasdemonstrated strong positive staining (+++) with Mab MAB 266.19.1.10.5.2and WT pancreas showed no staining (−).

Comparison of polyclonal and monoclonal antibodies. The anti-IL-22polyclonal antibody (Example 16) was shown to be sensitive, whereasmonoclonal antibody MAB 266.19.1.10.5.2 was specific. The polyclonalantibody showed positive staining on human IL-22 expressing BHK cells(+++), on murine IL-22 expressing BHK cells (+), in various human andmouse tissue samples (+), and in the islets of INS mIL-22 TG mice (+++).A greater percentage of the islets of the transgenics (vs. wild-type)contained positive staining. The staining in the transgenic islets wasgenerally distributed throughout the islet (+++) while staining in thewild-type islets was generally limited to the periphery of the islet(+). However, this antibody also showed non-specific staining on the WTBHK negative control cells (+).

MAB 266.19.1.10.5.2 showed positive staining on human IL-22 expressingBHK cells (+++), on murine IL-22 expressing BHK cells (+), and in theislets of INC mIL-22 TG mice (+++). The staining in the transgenicislets was generally distributed throughout the islet (+++) while thewild-type islets demonstrated negative staining (−).

EXAMPLE 21 IL-20 is Upregulated in Human Psoriatic Skin Samples

A. RNA Samples

Normal skin samples as well as skin from psoriasis patients wereobtained. The latter included involved skin from psoriasis and fromadjacent uninvolved skin. RNA was isolated from human skin samples usingconventional methods. The integrity and quality of RNA samples wastested on the Agilent 2100 Bioanalyzer (Agilent Technologies, WaldbronnGermany).

B. Primers and Probes for Quantitative RT-PCR

Real-time quantitative RT-PCR using the ABI PRISM 7700 SequenceDetection System (PE Applied Biosystems, Inc., Foster City, Calif.) hasbeen previously described (See, Heid, C. A. et al., Genome Research6:986-994, 1996; Gibson, U. E. M. et al., Genome Research 6:995-1001,1996; Sundaresan, S. et al., Endocrinology 139:4756-4764, 1998. Thismethod incorporates use of a gene specific probe containing bothreporter and quencher fluorescent dyes. When the probe is intact thereporter dye emission is negated due to the close proximity of thequencher dye. During PCR extension using additional gene-specificforward and reverse primers, the probe is cleaved by the 5′ to 3′nucleolytic activity of the rTth DNA Polymerase which releases thereporter dye from the probe resulting in an increase in fluorescentemission.

The primers and probes used for real-time quantitative RT-PCR analysesof IL-20 expression were designed using the primer design softwarePrimer Express™ (PE Applied Biosystems, Foster City, Calif.). Theforward primer, ZC40541 (SEQ ID NO:25) and the reverse primer, ZC 40542(SEQ ID NO:26) were used in a PCR reaction (below) at a 800 nMconcentration to synthesize a 71 bp product. The corresponding IL-20TaqMan® probe, ZC 40544 (SEQ ID NO:27) was synthesized and labeled by PEApplied Biosystems. The IL-20 probe was labeled at the 5′ end with areporter fluorescent dye (6-carboxy-fluorescein) (FAM) (PE AppliedBiosystems) and at the 3′ end with a quencher fluorescent dye(6-carboxy-tetramethyl-rhodamine) (TAMRA) (PE Applied Biosystems).

C. Real-time Quantitative RT-PCR

Relative levels of IL-20 mRNA were determined by analyzing total RNAsamples using the TaqMan EZ RT-PCR Core Reagents Kit (PE AppliedBiosystems). Runoff IL-20 transcript was made to generate a standardcurve used for quantitation. The curve consisted of 10-fold serialdilutions ranging from about 1e8 to 1e3 total copies of whole messagefor IL-20 with each standard curve point analyzed in triplicate. Thetotal RNA samples from skin were also analyzed in triplicate for humanIL-20 transcript levels and for levels of hGUS as an endogenous control.In a total volume of 25 μl, each RNA sample was subjected to TaqMan EZRT-PCR reaction (PE Applied Biosystems) containing: approximately 25 ngof total RNA in DEPC treated water (Dnase/Rnase free); appropriateprimers (approximately 800 nM ZC40541 (SEQ ID NO:25) and ZC40542 (SEQ IDNO:26); appropriate probe (approximately 100 nM ZC40544 (SEQ ID NO:27);1× TaqMan EZ Buffer; 3 mM Manganese acetate; 300 μM each d-CTP, d-ATP,and d-GTP and 600 μM of d-UTP; rTth DNA Polymerase (0.1 U/μl); andAmpErase UNG (0.01 U/μl). PCR thermal cycling conditions were asfollows: an initial UNG treatment step of one cycle at 50° C. for 2minutes; followed by a reverse transcription (RT) step of one cycle at60° C. for 30 minutes; followed by a deactivation of UNG step of onecycle at 95° C. for 5 minutes; followed by 40 cycles of amplification at94° C. for 20 seconds and 60° C. for 1 minute.

Relative IL-20 RNA levels were determined by using the Standard CurveMethod as described by the manufacturer, PE Biosystems (User Bulletin#2: ABI Prism 7700 Sequence Detection System, Relative Quantitation ofGene Expression, Dec. 11, 1997). The hGUS measurements were used tonormalize IL-20 levels. Data are shown in Table 13 below.

TABLE 13 Skin Sample IL-20 Normal 2903 Uninvolved 7233 Involved 27,695

Although IL-20 mRNA was detectable in skin samples from normal patientsor from uninvolved areas, there was upregulation for IL-20 message ininvolved skin from psoriasis patients. The receptor subunits for IL-20,including IL-20RA, IL-22RA (IL-22RA), and IL-20RB were expressed inhuman normal and diseased skin. These data support a strong diseaseassociation for IL-20 to human psoriasis.

Overexpression of IL-20 was shown in human psoriatic lesions, suggestingthat IL-20 is involved in human psoriasis. Moreover, as describedherein, over expression of IL-20 in transgenic mice showed epidermalthickening and immune cell involvement indicative of a psoriaticphenotype. Such in vivo data further suggests that IL-20 is involved inpsoriasis. As such, antagonists to IL-20 activity, such as theanti-human-IL-22RA monoclonal antibodies of the present invention, aswell as soluble receptors and antibodies thereto, and anti-IL-20neutralizing and monoclonal antibodies, are useful therapeutically asantagonists to IL-20 in the treatment of inflammatory diseases, such aspsoriasis, as well as other indications as disclosed herein.

EXAMPLE 22 IL-20 is Upregulated in Human Atopic Dermatitis Skin Samples

A. RNA Samples

Normal skin samples as well as skin from atopic dermatitis patients wereobtained. RNA was isolated from human skin samples using conventionalmethods. The integrity and quality of RNA samples was tested on theAgilent 2100 Bioanalyzer (Agilent Technologies, Waldbronn Germany).

B. Primers and Probes for Quantitative RT-PCR

Real-time quantitative RT-PCR using the ABI PRISM 7700 SequenceDetection System (PE Applied Biosystems, Inc., Foster City, Calif.) hasbeen previously described (See, Heid, C. A. et al., Genome Research6:986-994, 1996; Gibson, U. E. M. et al., Genome Research 6:995-1001,1996; Sundaresan, S. et al., Endocrinology 139:4756-4764, 1998. Thismethod incorporates use of a gene specific probe containing bothreporter and quencher fluorescent dyes. When the probe is intact thereporter dye emission is negated due to the close proximity of thequencher dye. During PCR extension using additional gene-specificforward and reverse primers, the probe is cleaved by the 5′ to 3′nucleolytic activity of the rTth DNA Polymerase which releases thereporter dye from the probe resulting in an increase in fluorescentemission.

The primers and probes used for real-time quantitative RT-PCR analysesof IL-20 expression were designed using the primer design softwarePRIMER EXPRESS™ (PE Applied Biosystems, Foster City, Calif.). Theforward primer, ZC40541 (SEQ ID NO:25) and the reverse primer, ZC 40542(SEQ ID NO:26) were used in a PCR reaction (below) at a 800 nMconcentration to synthesize a 71 bp product. The corresponding IL-20TAQMAN® probe, ZC 40544 (SEQ ID NO:27) was synthesized and labeled by PEApplied Biosystems. The IL-20 probe was labeled at the 5′ end with areporter fluorescent dye (6-carboxy-fluorescein) (FAM) (PE AppliedBiosystems) and at the 3′ end with a quencher fluorescent dye(6-carboxy-tetramethyl-rhodamine) (TAMRA) (PE Applied Biosystems).

C. Real-time Quantitative RT-PCR

Relative levels of IL-20 mRNA were determined by analyzing total RNAsamples using the TaqMan EZ RT-PCR Core Reagents Kit (PE AppliedBiosystems). Runoff IL-20 transcript was made to generate a standardcurve used for quantitation. The curve consisted of 10-fold serialdilutions ranging from about 1e8 to 1e3 total copies of whole messagefor IL-20 with each standard curve point analyzed in triplicate. Thetotal RNA samples from skin were also analyzed in triplicate for humanIL-20 transcript levels and for levels of hGUS as an endogenous control.In a total volume of 25 μl, each RNA sample was subjected to TaqMan EZRT-PCR reaction (PE Applied Biosystems) containing: approximately 25 ngof total RNA in DEPC treated water (Dnase/Rnase free); appropriateprimers (approximately 800 nM ZC40541 (SEQ ID NO:25) and ZC40542 (SEQ IDNO:26); appropriate probe (approximately 100 nM ZC40544 (SEQ ID NO:27);1× TaqMan EZ Buffer; 3 mM Manganese acetate; 300 μM each d-CTP, d-ATP,and d-GTP and 600 μM of d-UTP; rTth DNA Polymerase (0.1 U/μl); andAmpErase UNG (0.01 U/μl). PCR thermal cycling conditions were asfollows: an initial UNG treatment step of one cycle at 50° C. for 2minutes; followed by a reverse transcription (RT) step of one cycle at60° C. for 30 minutes; followed by a deactivation of UNG step of onecycle at 95° C. for 5 minutes; followed by 40 cycles of amplification at94° C. for 20 seconds and 60° C. for 1 minute.

Relative IL-20 RNA levels were determined by using the Standard CurveMethod as described by the manufacturer, PE Biosystems (User Bulletin#2: ABI Prism 7700 Sequence Detection System, Relative Quantitation ofGene Expression, Dec. 11, 1997). The hGUS measurements were used tonormalize IL-20 levels.

IL-20 mRNA was detectable at a low level (about 800 copies) in skinsamples. In contrast, there was upregulation for IL-20 message in skinsfrom atopic dermatitis patients (about 8600 copies). The receptorsubunits for IL-20, including IL-20RA), IL-22RA, and IL-20RB areexpressed in human normal and diseased skin. These data support a strongdisease association for IL-20 to human atopic dermatitis.

Overexpression of IL-20 was shown in human atopic dermatitis skins,suggesting that IL-20 is involved in human atopic dermatitis. Moreover,as described herein, over expression of IL-20 in transgenic mice showedepidermal thickening and immune cell involvement indicative of an atopicdermatitis phenotype. Such in vivo data further suggests that IL-20 isinvolved in atopic dermatitis. As such, antagonists to IL-20 activity,such as the anti-human-IL-22RA monoclonal antibodies of the presentinvention, as well as soluble receptors and antibodies thereto, andanti-IL-20 neutralizing and monoclonal antibodies, are usefultherapeutically as antagonists to IL-20 in the treatment of inflammatorydiseases, such as atopic dermatitis, as well as other indications asdisclosed herein.

EXAMPLE 23 Up-regulation of IL-8 by IL-20

Normal Human Epidermal neonatal keratinocytes (NHEK) (from Clonetics) atpassage 2 were plated and grown to confluency in 12 well tissue cultureplates. KGM (Keratinocyte growth media) was purchased from Clonetics.When cells reached confluency, they were washed with KGM media minusgrowth factors=KBM (keratinocyte basal media). Cells were serum starvedin KBM for 72 hours prior to the addition of test compounds. Thrombin at1 I.U./mL and trypsin at 25 nM were used as positive controls. One mL ofmedia/well was added. KBM only was used as the negative control.

IL-20 was made up in KBM media and added at varying concentrations, from2.5 μg/ml down to 618 ng/mL in a first experiment and from 2.5 μg/mLdown to 3 ng/mL in a second experiment.

Cells were incubated at 37° C., 5% CO₂ for 48 hours. Supernatants wereremoved and frozen at −80° C. for several days prior to assaying forIL-8 and GM-CSF levels. Human IL-8 Immunoassay kit #D8050 (Rand DSystems, Inc.) and human GM-CSF Immunoassay kit #HSGMO (Rand D Systems,Inc.) were used to determine cytokine production followingmanufacturer's instructions.

The results indicated that the expression of IL-8 and GM-CSF wereinduced by IL-20.

EXAMPLE 24 Up-regulation of Inflammatory Cytokines by IL-20

The human keratinocyte cell line, HaCaT was grown at 37° C. to severaldays post-confluence in T-75 tissue culture flasks. At this point,normal growth media (DMEM+10% FBS) was removed and replaced withserum-free media. Cells were then incubated for two days at 37° C. DMEMwas then removed and four flasks of cells per treatment were treatedwith one of each of the following conditions for four hours at 37° C.:recombinant human (rh) IL-1 alpha at 5 ng/mL, rh IL-1 alpha at 20 ng/mL,rh IL-1 alpha at 5 ng/mL+IL-20 at 1 μg/mL, IL-20 at 1 μg/mL, or rh IL-10at 10 ng/mL.

Following cytokine treatment, media was removed and cells were lysedusing a guanidium thiocyanate solution. Total RNA was isolated from thecell lysate by an overnight spin on a cesium chloride gradient. Thefollowing day, the RNA pellet was resuspended in a TE/SDS solution andethanol precipitated. RNA was then quantitated using aspectrophotometer, followed by a DNase treatment as per Section V.B. ofClontech's ATLAS™ cDNA Expression Arrays User Manual (versionPT3140-1/PR9X390, published Nov. 5, 1999). Quality of RNA samples wasverified by purity calculations based on spec readings, and byvisualization on agarose gel. Genomic contamination of the RNA sampleswas ruled out by PCR analysis of the beta-actin gene.

Clontech's protocols for polyA+ enrichment, probe synthesis andhybridization to Atlas™ arrays were followed (see above, plus ATLAS™Pure Total RNA Labeling System User Manual, PT3231-1/PR96157, publishedJun. 22, 1999). Briefly, polyA+ RNA was isolated from 50 mg of total RNAusing streptavidin coated magnetic beads (by Clontech, Paolo Alto,Calif.) and a magnetic particle separator. PolyA+ RNA was then labeledwith ^(alpha32)P-dATP via RT-PCR. Clontech CDS primers specific to the268 genes on the ATLAS™ human cytokine/receptor array (Cat. #7744-1)were used in the reaction. Labeled probe was isolated using columnchromatography and counted in scintillation fluid.

ATLAS™ arrays were pre-hybridized with Clontech ExpressHyb plus 100mg/mL heat denatured salmon sperm DNA for at least thirty minutes at 68°C. with continuous agitation. Membranes were then hybridized with1.9×10⁶ CPM/mL (a total of 1.14×10⁷ CPM) overnight at 68° C. withcontinuous agitation. The following day, membranes were washed forthirty minutes×4 in 2×SSC, 1% SDS at 68° C., plus for thirty minutes×1in 0.1×SSC, 0.5% SDS at 68° C., followed by one final room temperaturewash for five minutes in 2×SSC. Array membranes were then placed inKodak plastic pouches sealed and exposed to a phosphor imager screenovernight at room temperature. The next day, phosphor screens werescanned on a phosphor imager and analyzed using Clontech's ATLASIMAGE™1.0 software.

Genes Up-regulated by IL-20:

-   1. Tumor necrosis factor (TNF) was up-regulated 1.9-2.4 fold by    IL-20.-   2. Placental growth factors 1 & 2 (PLGF) were up-regulated 1.9-2.0    fold by IL-20.-   3. Coagulating factor II receptor was up-regulated 2.0-2.5 fold by    IL-20.-   4. Calcitonin receptor was up-regulated 2.2-2.3 fold by IL-20.-   5. TNF-inducible hyaluronate-binding protein TSG-6 was up-regulated    2.1-2.2 fold by IL-20.-   6. Vascular endothelial growth factor (VEGF) receptor-1 precursor,    tyrosine-protein kinase receptor (FLT-1) (SFLT) was up-regulated    2.1-2.7 fold by IL-20.-   7. MRP-8 (calcium binding protein in macrophages MIF-related) was    up-regulated 2.9-4.1 fold by IL-20.-   8. MRP-14 (calcium binding protein in macrophages MIF-related) was    up-regulated 3.0-3.8 fold by IL-20.-   9. Relaxin H2 was up-regulated 3.14 fold by IL-20.-   10. Transforming growth factor beta (TGFβ) receptor III 300 kDa was    up-regulated 2.4-3.6 fold by IL-20.    Genes Showing Synergy with IL-20+IL-1 Treatment:-   1. Bone morphogenic protein 2a was up-regulated 1.8 fold with IL-20    treatment alone, 2.5 fold with IL-1 treatment alone, and 8.2 fold    with both IL-20 and IL-1 treatment together.-   2. MRP-8 was up-regulated 2.9 fold with IL-20 treatment alone, 10.7    fold with IL-1 treatment alone and 18.0 fold with both IL-20 and    IL-1 treatment together.-   3. Erythroid differentiation protein (EDF) was up-regulated 1.9 fold    with IL-20 treatment alone, 9.7 fold with IL-1 treatment alone and    19.0 fold with both IL-20 and IL-1 treatment together.-   4. MRP-14 (calcium binding protein in macrophages, MIF related) was    up-regulated 3.0 fold with IL-20 treatment alone, 12.2 fold with    IL-1 treatment alone and 20.3 fold with both IL-20 and IL-1    treatment together.-   5. Heparin-binding EGF-like growth factor was up-regulated 2.0 fold    with IL-20 treatment alone, 14 fold with IL-1 treatment alone and    25.0 fold with both IL-20 and IL-1 treatment together.-   6. Beta-thromboglobulin-like protein was up-regulated 1.5 fold with    IL-20 treatment alone, 15 fold with IL-1 treatment alone and 27 fold    with both IL-20 and IL-1 treatment together.-   7. Brain-derived neurotrophic factor (BDNF) was up-regulated 1.7    fold with IL-20 treatment alone, 25 fold with IL-1 treatment alone    and 48 fold with both IL-20 and IL-1 treatment together.-   8. Monocyte chemotactic and activating factor MCAF was up-regulated    1.3 fold with IL-20 treatment alone, 32 fold with IL-1 treatment    alone and 56 fold with both IL-20 and IL-1 treatment together.

EXAMPLE 25 IL-20 Transgenic Phenotype

Both human and mouse IL-20 were overexpressed in transgenic mice using avariety of promoters. The liver-specific mouse albumin promoter,directing expression of human IL-20, was used initially in an attempt toachieve circulating levels of protein. Subsequent studies were conductedusing the keratin 14 (K14) promoter, which primarily targets expressionto the epidermis and other stratified squamous epithelia; the mousemetallothionein-1 promoter, which gives a broad expression pattern; andthe EμLCK promoter, which drives expression in cells of the lymphoidlineage. Similar results were obtained in all four cases, possiblybecause these promoters all give rise to circulating levels of IL-20.

In all cases, transgenic pups expressing the IL-20 transgene weresmaller than non-transgenic littermates, had a shiny appearance withtight, wrinkled skin and died within the first few days after birth.Pups had milk in their stomachs indicating that they were able tosuckle. These mice had swollen extremities, tail, nostril and mouthregions and had difficulty moving. In addition, the mice were frail,lacked visible adipose tissue and had delayed ear and toe development.Low expression levels in liver (less than 100 mRNA molecules/cell) weresufficient for both the neonatal lethality and skin abnormalities.Transgenic mice without a visible phenotype either did not express thetransgene, did not express it at detectable levels, or were mosaic.

Histologic analysis of the skin of the IL-20 transgenic mice showed athickened epidermis, hyperkeratosis and a compact stratum corneumcompared to non-transgenic littermates. Serocellular crusts (scabs) wereobserved occasionally. Electron microscopic (EM) analysis of skin fromtransgenic mice showed intramitochondrial lipoid inclusions, mottledkeratohyaline granules, and relatively few tonofilaments similar to thatobserved in human psoriatic skin and in mouse skin disease models. Inaddition, many of the transgenic mice had apoptotic thymic lymphocytes.No other abnormalities were detected by histopathological analysis.These histological and EM results support and extend the observed grossskin alterations.

EXAMPLE 26 Construction of Expression Vector for Expression of SolubleHuman IL-22RA-muFc

A human IL-22RA soluble receptor-muFc fusion (denoted as IL-22RA-C(mG2a)containing the extracellular domain of IL-22RA fused to the murine gamma2a heavy chain Fc region (mG2a), was prepared. An expression plasmidcontaining IL-22RA—C(mG2a) was constructed via homologous recombinationusing two separate DNA fragments and the expression vector pZMP40.Fragments of polynucleotide sequence of IL-22RA (SEQ ID NO:1), and mG2aSEQ ID NO:39 were generated by PCR amplification using the followingprimers: (a) IL-22RA primers ZC45,593 (SEQ ID NO:28), and ZC45,592 (SEQID NO:29); and (b) mG2a primers ZC45,591 (SEQ ID NO:30), and ZC45,594(SEQ ID NO:31).

The first fragment contained the IL-22RA extracellular domain codingregion, which was made using an IL-22RA polynucleotide (e.g., SEQ IDNO:1) as the template. The first fragment included a 5′ overlap with apartial pZMP40 vector sequence, the IL-22RA segment, and a 3′ overlapcontaining a linker sequence and partial mG2a sequence. PCR conditions:1 cycle, 94° C., 5 minutes; 35 cycles, 94° C., 1 minute, followed by 55°C., 2 minutes, followed by 72° C., 3 minutes; 1 cycle, 72° C., 10minutes.

The second fragment included a 5′ overlap with a linker sequence andpartial IL-22RA sequence, the mG2a segment, and a 3′ overlap containinga partial pZMP40 vector sequence. The murine gamma 2a heavy chain Fcregion (mG2a) (SEQ ID NO:39) was generated from a clone of murine Iggamma 2a heavy chain cDNA. The mG2a contains the hinge, C_(H)2, andC_(H)3 domains of the murine immunoglobulin gamma 2a heavy chainconstant region. PCR conditions: 1 cycle, 94° C., 5 minutes; 35 cycles,94° C., 1 minute, followed by 55° C., 2 minutes, followed by 72° C., 3minnutes; 1 cycle, 72° C., 10 minutes.

The PCR reaction mixtures were run on a 1% agarose gel and a bandcorresponding to the sizes of the inserts were gel-extracted using aQIAQUICK™ Gel Extraction Kit (Qiagen).

The plasmid pZMP40, which was cut with BglII, was used in a three-wayrecombination with both of the PCR insert fragments. Plasmid pZMP40 is amammalian expression vector containing an expression cassette having theMPSV promoter, and multiple restriction sites for insertion of codingsequences; an E. coli origin of replication; a mammalian selectablemarker expression unit comprising an SV40 promoter, enhancer and originof replication, a DHFR gene, and the SV40 terminator; and URA3 andCEN-ARS sequences required for selection and replication in S.cerevisiae. Plasmid pZMP40 was constructed from pZMP21 (deposited at theAmerican Type Culture Collection, 10801 University Boulevard, Manassas,Va. 20110-2209, and designated No. PTA-5266) by addition of severalrestriction enzyme sites to the polylinker.

One hundred microliters of competent yeast (S. cerevisiae) cells wereindependently combined with 10 μl of the insert DNA and 100 ng of cutpZMP40 vector, and the mix was transferred to a 0.2-cm electroporationcuvette. The yeast/DNA mixture was electropulsed using power supply(BioRad Laboratories, Hercules, Calif.) settings of 0.75 kV (5 kV/cm), ∞ohms, and 25 μF. Six hundred μl of 1.2 M sorbitol was added to thecuvette, and the yeast was plated in a 100-μl and 300 μl aliquot ontotwo URA-D plates and incubated at 30° C. After about 72 hours, the Ura⁺yeast transformants from a single plate were resuspended in 1 ml H₂O andspun briefly to pellet the yeast cells. The cell pellet was resuspendedin 0.5 ml of lysis buffer (2% Triton X-100, 1% SDS, 100 mM NaCl, 10 mMTris, pH 8.0, 1 mM EDTA). The five hundred microliters of the lysismixture was added to an Eppendorf tube containing 250 μl acid-washedglass beads and 300 μl phenol-chloroform, was vortexed for 3 minutes,and spun for 5 minutes in an Eppendorf centrifuge at maximum speed.Three hundred microliters of the aqueous phase was transferred to afresh tube, and the DNA was precipitated with 600 μl ethanol (EtOH) and30 μl 3M sodium acetate, followed by centrifugation for 30 minutes atmaximum speed. The tube was decanted and the pellet was washed with 1 mLof 70% ethanol. The tube was decanted and the DNA pellet was resuspendedin 30 μl TE.

Transformation of electrocompetent E. coli host cells (DH12S) was doneusing 5 μl of the yeast DNA prep and 50 μl of cells. The cells wereelectropulsed at 2.0 kV, 25 μF, and 400 ohms. Following electroporation,1 ml SOC (2% BACTO™ Tryptone (Difco, Detroit, Mich.), 0.5% yeast extract(Difco), 10 mM NaCl, 2.5 mM KCl, 10 mM MgCl₂, 10 mM MgSO₄, 20 mMglucose) was added and then the cells were plated in a 50 μl and 200 μlaliquot on two LB AMP plates (LB broth (Lennox), 1.8% Bacto™ Agar(Difco), 100 mg/L Ampicillin).

The inserts of three clones for the construct was subjected to sequenceanalysis and one clone for each construct, containing the correctsequence, was selected. Larger scale plasmid DNA was isolated using acommercially available kit (QIAGEN Plasmid Mega Kit, Qiagen, Valencia,Calif.) according to manufacturer's instructions.

EXAMPLE 27 Expression and Purification of Human Soluble IL-22RA-muFcPolypeptide

Three sets of 200 μg of the IL-22RA-C(mG2a) construct (Example 22) wereeach digested with 200 units of Pvu I at 37° C. for three hours and thenwere precipitated with IPA and spun down in a 1.5 mL microfuge tube. Thesupernatant was decanted off the pellet, and the pellet was washed with1 mL of 70% ethanol and allowed to incubate for 5 minutes at roomtemperature. The tube was spun in a microfuge for 10 minutes at 14,000RPM and the supernatant was decanted off the pellet. The pellet was thenresuspended in 750 μl of PF-CHO media in a sterile environment, andallowed to incubate at 60° C. for 30 minutes. 5E6 APFDXB11 cells werespun down in each of three tubes and were resuspended using theDNA-media solution. The DNA/cell mixtures were placed in a 0.4 cm gapcuvette and electroporated using the following parameters: 950 μF, highcapacitance, and 300 V. The contents of the cuvettes were then removed,pooled, and diluted to 25 mLs with PF-CHO media and placed in a 125 mLshake flask. The flask was placed in an incubator on a shaker at 37° C.,6% CO₂, and shaking at 120 RPM.

The cell line was subjected to nutrient selection followed by stepamplification to 100 nM methotrexate (MTX), then to 500 nM MTX, andfinally to 1 μM MTX. Step amplification was followed by a CD8 cell sort.The CD8 cell sort was accomplished by taking a stable 1 μM MTX amplifiedpool and staining approximately 5E6 cells with a monoclonal FITCanti-CD8 antibody (BD PharMingen, cat# 30324X) using manufacturersrecommended concentration. The stained cells were processed and sortedon a FACS Vantage (BD) flow cytometer. The top 5% of cells werecollected and outgrown. Expression was confirmed by western blot, andthe cell line was scaled-up and protein purification using standardmethods followed.

EXAMPLE 28 Neutralization of huIL-22RA by Sera from Mice Immunized withhuL22RA-mG2a

A. Cell-based Neutralization Assay to Test for Inhibition of IL-20and/or IL-22.

The factor-dependent pre-B cell line BaF3 co-transfected with IL-22RAand IL-20RB (pDIRS1) (BAF/IL-22RA/IL-20RB cells; Example 38) was used toassess neutralization potential of anti-IL-22RA antibodies byantagonizing IL-20 on the IL-22RA/IL-20RB receptor. Similarly, BaF3co-transfected with IL-22RA and IL-10RB (CRF2-4) (BAF/IL-22RA/CRF2-4cells; Example 2) was used to assess neutralization potential ofanti-IL-22RA antibodies by antagonizing IL-22 on the IL-22RA/IL10RBreceptor. Proliferation in the presence of IL-20 or IL22 on itsrespective receptor-expressing cell line, and inhibition of suchproliferation in the presence of the antagonist antibodies, was assessedusing an Alamar blue assay as described in Example 3. Inhibition ofproliferation on these cells is indicative of neutralizing activity inthis assay.

B. Anti-IL-22RA Serum Neutralizes both IL-20 and IL-22 in Cell-basedNeutralization Assay.

Using the assay described in Example 28A, serum from IL-22RA knockoutmice immunized with huIL-22RA-muG2a (Example 30(A)(1)) was added as aserial dilution at 1%, 0.5%, 0.25%, 0.13%, 0.06%, 0.03%, 0.02%, and 0%.The assay plates were incubated at 37° C., 5% CO₂ for 4 days at whichtime Alamar Blue (Accumed, Chicago, Ill.) was added at 20 μl/well.Plates were again incubated at 37° C., 5% CO₂ for 16 hours. Alamar Bluegives a fluorometric readout based on number of live cells, and is thusa direct measurement of cell proliferation in comparison to a negativecontrol. Plates were read on the Wallac Victor 2 1420 Multilabel Counter(Wallac, Turku, Finland) at wavelengths 530 (Excitation) and 590(Emission). Results showed that serum from all seven immunized animalscould neutralize signaling of both huIL-22 and huIL20 through huIL-22RA.For example, at the 1% concentration, serum from five animals (16517,16518, 16519, 16520, and 16527) completely neutralized proliferationinduced by huIL-22, with the inhibition of proliferation decreasing in adose dependent fashion at the lower concentrations. Moreover, at the 1%concentration, serum from the other two animals (16471 and 16701)inhibited about 90% of the proliferation induced by huIL-22, with theinhibition of proliferation decreasing in a dose dependent fashion atthe lower concentrations. Similarly, at the 1% and 0.5% concentrations,serum from five animals (16517, 16518, 16519, 16520, and 16527)completely neutralized proliferation induced by huIL-20, with theinhibition of proliferation decreasing in a dose dependent fashion atthe lower concentrations. Moreover, at the 1% concentration, serum fromanimal 16701 completely neutralized proliferation induced by huIL-20,with the inhibition of proliferation decreasing in a dose dependentfashion at the lower concentrations. At the 1% concentration, serum fromanimal 16471 neutralized about 95% of the proliferation induced byhuIL-20, with the inhibition of proliferation decreasing in a dosedependent fashion at the lower concentrations. Thus, sera from all sevenanimals were able to neutralize the proliferation induced by eitherIL-20 or IL-22 through the huIL-22RA receptor. These results furtherdemonstrated that antibodies to IL-22RA could indeed antagonize theactivity of the pro-inflammatory ligands, IL-20 and IL-22 at lowconcentrations.

These results provided additional evidence that effectively blockingIL-22RA activity by binding, blocking, inhibiting, reducing,antagonizing or neutralizing IL-20 or IL-22 activity (individually ortogether), for example via a neutralizing monoclonal antibody to IL-22RAof the present invention, could be advantageous in reducing the effectsof IL-20 and IL-22 (alone or together) in vivo and may be reduce IL-20and/or IL-22-induced inflammation, such as that seen in IL-20-inducedskin effects, as well as IL-22-induced skin effects, for example inpsoriasis, IBD, colitis, or other inflammatory diseases induced byIL-20, and or IL-22 including IBD, arthritis, asthma, psoriaticarthritis, colitis, inflammatory skin conditions, and atopic dermatitis.

EXAMPLE 29 Generation of P815/hIL-22RA Cells and Immunization of Mice

A. P815/hIL-22RA Cell Generation and Injection into Mice for Generationof Anti-hIL-22RA Antibodies:

WT P815 Cells (ATCC No. TIB-64) were transfected with a plasmid vectorcontaining the hIL-22RA cDNA sequence (e.g., SEQ ID NO:1) and aselectable puromycin-resistance marker, using Fugene Reagent accordingto the manufacturer's protocol (Roche, Indianapolis, Ind.). Cells wereplaced under Puromycin selection 48 hours following transfection.Puromycin-resistant transfectants were cloned by limiting dilution, andscreened for their level of hIL-22RA cell surface expression by flowcytometry, using biotinylated human IL-22 (huIL-22-biotin). Briefly,cells were incubated with 5 ug/ml huIL-22-biotin for 30 minutes on iceand then washed. Binding of huIL-22-biotin to the cells was thendetected using PE-labeled streptavidin at 1:500. Cells were analyzed ona Facscan flow cytometer using Cellquest software. (Becton Dickinson,San Jose, Calif.).

The selected P815/IL-22RA cell clone was grown up and then harvested forinjection. Cells were collected, washed three times in PBS, counted,resuspended at 1×10⁸ cells per milliliter, and irradiated with 10,000rads. The cell suspension was then transferred to a 1 ml syringe, andinjected by the intra-peritoneal route into DBA/2 Mice. Mice wereboosted in an identical manner 3 weeks later and sera were screened forbinding to hIL-22RA transfectant cell line. Briefly, sera were diluted1:100 in Facs buffer (HBSS, 2% BSA, 0.02% NaN₃), and then incubated withFc-blocked 293 human kidney cells over-expressing hIL-22RA. Binding ofanti-IL-22RA antibodies to the cells was then detected usingfluorescein-conjugated Goat-anti-Mouse IgG diluted to 1:200. (SouthernBiotech, Birmingham, Ala.) Cells were analyzed as described previously.Mice were boosted again a total of 3 more times and sera were screenedas described. Two mice were selected for hybridoma fusion, usingstandard methods in the art for generation of monoclonal antibodies(Example 25), based on the level of their serum binding to the hIL-22RAtransfectants.

The above method is also used for generation of P815 cells expressingheterodimeric IL-22RA receptors, such as IL-22RA/CRF2-4(P815/IL-22RA/CRF2-4 cells), IL-22RA/pDIRS1 (P815/IL-22RA/pDIRS1 cells),or IL-22RA/CRF2-4/pDIRS1 (P815/IL-22RA/CRF2-4/pDIRS1 cells), for exampleto immunize mice for the generation of monoclonal antibodies againstIL-22RA and IL-22RA-comprising heterodimeric receptors.

EXAMPLE 30 Generation of Murine Anti-human IL-22RA (IL-22RA) mAbs

A. Immunization for Generation of Anti-IL-22RA Antibodies:

(1) Using Soluble IL-22RA-muFc

Six to twelve week old IL-22RA knockout mice (Example 26) were immunizedby intraperitoneal injection with 25-50 ug of soluble human IL-22RA-muFcprotein (Example 23) mixed 1:1 (v:v) with Ribi adjuvant (Sigma) on abiweekly schedule. Seven to ten days following the third immunization,blood samples were taken via retroorbital bleed, the serum harvested andevaluated for its ability to inhibit the binding of IL-22 or both IL-20and IL-22 to IL-22RA in neutralization assays (e.g., described herein)and to stain IL-22RA transfected versus untransfected 293 cells in aFACS staining assay. Mice continued to be immunized and blood samplestaken and evaluated as described above until neutralization titersreached a plateau. At that time, mice with the highest neutralizationtiters were injected intravascularly with 25-50 ug of soluble IL-22RA-Fcprotein in PBS. Three days later, the spleen and lymph nodes from thesemice were harvested and used for hybridoma generation, for example usingmouse myeloma (P3-X63-Ag8.653.3.12.11) cells or other appropriate celllines in the art, using standard methods known in the art (e.g., seeKearney, J. F. et al., J Immunol. 123:1548-50, 1979; and Lane, R. D. JImmunol Methods 81:223-8, 1985).

(2) Using P815 Transfectants that Express the IL-22RA Receptor.

Six to ten week old female DBA/2 mice are immunized by intraperitonealinjection of 1×10⁵ live, transfected P815 cells, for exampleP815/IL-22RA cells, P815/IL-22RA/CRF2-4, P815/IL-22RA/pDIRS1 orP815/IL-22RA/CRF2-4/pDIRS1 cells (Example 24) (e.g., 0.5 ml at a celldensity of 2×10⁵ cells/ml). Prior to injection, the cells are maintainedin the exponential growth phase. For injection the cells are harvested,washed three times with PBS and then resuspended in PBS to a density of2×10⁵ cells/ml. In this model, the mice develop an ascites tumor within2-3 weeks and progress to death by 4-6 weeks unless an immune responseto the transfected target antigen has been mounted. At three weeks micewith no apparent abdominal swelling (indicative of ascites) arere-immunized as above at 2-3 week intervals. Seven to ten days followingthe second immunization, blood samples are taken via retroorbital bleed,the serum harvested and evaluated for its ability to inhibit the bindingof IL-22 or both IL-20 and IL-22 to IL-22RA in neutralization assays(e.g., described herein) and to stain IL-22RA transfected versusuntransfected 293 cells in a FACS staining assay. Mice continue to beimmunized and blood samples taken and evaluated as described above untilneutralization titers reach a plateau. At that time, the mice with thehighest neutralization titers are injected intraperitonealy with 1×10⁵live, transfected P815 cells. Four days later, the spleen and lymphnodes from these mice are harvested and used for hybridoma generation,for example using mouse myeloma (P3-X63-Ag8.653.3.12.11) cells or otherappropriate cell lines in the art, using standard methods known in theart (e.g., see Kearney, J. F. et al., supra.; and Lane, R. D. supra.).

An alternative to the above immunization scheme with live, transfectedP815 cells involves intraperitoneal injection of 1-5×10⁶ irradiated,transfected cells every 2-3 weeks. In this approach, no animals developand die of ascites. Instead, animals are monitored for a neutralizingimmune response to IL-22RA in their serum as outlined above, startingwith a bleed after the second immunization. Once neutralization titershave reached a maximal level, the mice with highest titers are given apre-fusion, intraperitoneal injection of 5×10⁶ irradiated cells and fourdays later, the spleen and lymph nodes from these mice are harvested andused for hybridoma generation, for example using mouse myeloma(P3-X63-Ag8.653.3.12.11) cells or other appropriate cell lines in theart, using standard methods known in the art (e.g., see Kearney, J. F.et al., supra.; and Lane, R. D. supra.).

B. Screening the Hybridoma Fusions for Antibodies that Bind IL-22RA andInhibit the Binding of IL-22 to IL-22RA:

Two different primary screens were performed on the hybridomasupernatants at 8-10 days post-fusion. For the first assay, antibodiesin supernatants were tested for their ability to bind to plate boundsoluble human IL-22RA-muFc protein by ELISA using HRP-conjugated goatanti-mouse kappa and anti-lambda light chain second step reagents toidentify bound mouse antibodies. To demonstrate specificity for theIL-22RA portion of the IL-22RA-muFc protein, positive supernatants inthe initial assay were evaluated on an irrelevant protein fused to thesame murine Fc region (mG2a). Antibody in those supernatants that boundto IL-22RA-muFc and not the irrelevant muFc containing fusion proteinwere deemed to be specific for IL-22RA. For the second assay, antibodiesin all hybridoma supernatants were evaluated by ELISA for their abilityto inhibit the binding of biotinylated human IL-22 to plate boundIL-22RA-muFc.

All supernatants containing antibodies that bound specifically toIL-22RA, whether they inhibited the binding of IL-22 to IL-22RA or notin the ELISA assay, were subsequently tested for their ability toinhibit the binding (and concomitant pro-proliferative effect) of IL-20or IL-22 to IL-22RA/IL-20RB and IL-22RA/CRF2-4 transfected Baf3 cells,respectively. All supernatants that were neutralization positive ineither the IL-22 inhibition assay or both the IL-20 and IL-22 inhibitionassays were subsequently evaluated for their ability to stain IL-22RAtransfected versus untransfected Baf3 cells by FACS analysis. Thisanalysis was designed to confirm that inhibition of IL-22 binding toIL-22RA/CRF2-4, or IL-20 binding to IL-22RA/IL-20RB, was indeed due toan antibody that specifically binds the IL-22RA receptor. Additionally,since the FACS analysis was performed with an anti-IgG second stepreagent, specific FACS positive results indicate that the neutralizingantibody was likely to be of the IgG class. By these means, a masterwell was identified that bound IL-22RA in the plate bound ELISA,inhibited the binding of IL-22 to IL-22RA in the ELISA based inhibitionassay, blocked the interaction of IL-20 and IL-22 with IL-22RA/IL-20RBand IL-22RA/CRF2-4 transfected Baf3 cells (Example 28), respectively,and was strongly positive for the staining of both IL-22RA/IL-20RB andIL-22RA/CRF2-4 transfected Baf3 cells with an anti-mouse IgG second stepreagent.

C. Cloning Anti-IL-22RA Specific Antibody Producing Hybridomas:

A hybridoma producing an anti-IL-22RA mAb that cross-neutralized thebinding of IL-20 and IL-22 to appropriately transfected BaF3 cells wascloned by a standard low-density dilution (less than 1 cell per well)approach. Approximately 5-7 days after plating, the clones were screenedby ELISA on plate bound human IL-22RA-muFc followed by a retest ofpositive wells by ELISA on irrelevant muFc containing fusion protein asdescribed above. Selected clones, whose supernatants bound toIL-22RA-muFc and not the irrelevant muFc containing fusion protein, werefurther confirmed for specific antibody activity by repeating bothneutralization assays as well as the FACS analysis. All selected IL-22RAantibody positive clones were cloned a minimum of two times to helpinsure clonality and to assess stability of antibody production. Furtherrounds of cloning were performed and screened as described until,preferably, at least 95% of the resulting clones were positive forneutralizing anti-IL-22RA antibody production.

D. Biochemical Characterization of the Molecule Recognized byAnti-IL-22RA mAbs:

Biochemical confirmation that the target molecule, IL-22RA, recognizedby the putative anti-IL-22RA mAbs is indeed IL-22RA are performed bystandard immunoprecipitation followed by SDS-PAGE analysis or westernblotting procedures, both employing soluble membrane preparations fromIL-22RA transfected versus untransfected Baf3 cells. Moreover, solublemembrane preparations of non-transfected cell lines that express IL-22RAare used show that the mAbs recognize the native receptor chain as wellas the transfected one. Alternatively, the mAbs are tested for theirability to specifically immunoprecipitate or western blot the solubleIL-22RA-muFc protein.

EXAMPLE 31 Neutralization of huL22RA by Sera from Mice Injected withP815 Cells Transfected with huL22RA

Using the cell based neutralization assay described in Example 28, Serumfrom mice injected with live huIL-22RA transfected P815 cells (Example30.A.2) was added as a serial dilution at 1%, 0.5%, 0.25%, 0.13%, 0.06%,0.03%, 0.02%, and 0%. The assay plates were incubated at 37° C., 5% CO₂for 4 days at which time Alamar Blue (Accumed, Chicago, Ill.) was addedat 20 μl/well. Plates were again incubated at 37° C., 5% CO₂ for 16hours. Results showed that serum from four of the animals couldneutralize signalling of both huIL-22 and huIL20 through huIL-22RA.

At the 1% concentration, serum from six animals (7125, 7127, 7128, 7118,7124 and 7117) neutralized between 50% and 80% of the proliferationinduced by huIL-22, with the inhibition of proliferation decreasing in adose dependent fashion at the lower concentrations. Moreover, at the 1%concentration, serum from four animals (7125, 7127, 7118, and 7117)neutralized between 40% and 70% of the proliferation induced by huIL20,with the inhibition of proliferation decreasing in a dose dependentfashion at the lower concentrations. These results further demonstratedthat antibodies to IL-22RA could indeed antagonize the activity of thepro-inflammatory ligands, IL-20 and IL-22 at low concentrations.

These results provided additional evidence that effectively blockingIL-22RA activity by binding, blocking, inhibiting, reducing,antagonizing or neutralizing IL-20 or IL-22 activity (individually ortogether), for example via a neutralizing monoclonal antibody to IL-22RAof the present invention, could be advantageous in reducing the effectsof IL-20 and IL-22 (alone or together) in vivo and may be reduce IL-20and/or IL-22-induced inflammation, such as that seen in IL-20-inducedskin effects, as well as IL-22-induced skin effects, for example inpsoriasis, IBD, colitis, or other inflammatory diseases induced byIL-20, and or IL-22 including IBD, arthritis, asthma, psoriaticarthritis, colitis, inflammatory skin conditions, and atopic dermatitis.

EXAMPLE 32 Phenotype of IL-22RA Knockout Mice

A. Generation of Mice Carrying Genetic Modifications

1. Generation of Transgenic Mice Expressing Murine IL-20 with a NeonateShine

a). Construct for Expressing Murine IL-20 from the K14 Promoter.

In order to investigate biological function of IL-20 in vivo, atransgenic construct was made, in which murine IL-20 was driven by humanK14 promoter (also see, Example 21). Oligonucleotides were designed togenerate a PCR fragment containing a consensus Kozak sequence and themurine IL-20 coding region. These oligonucleotides were designed with anFseI site at the 5′ end and an AscI site at the 3′ end to facilitatecloning into pRSK14, a standard transgenic vector, containing a humankeratinocyte and epithelial cell-specific promoter.

PCR reactions were carried out with about 200 ng murine IL-20 template(SEQ ID NO:33) and oligonucleotides designed to amplify the full-lengthof the IL-20 (SEQ ID NO:34). PCR reaction conditions were determinedusing methods known in the art. PCR products were separated by agarosegel electrophoresis and purified using a QIAQUICK™ (Qiagen) gelextraction kit. The isolated, correct sized DNA fragment was digestedwith FseI and AscI (Boerhinger-Mannheim), ethanol precipitated andligated into pRSK14, previously digested with FseI and AscI. The pRSK14plasmid, designed for expressing a gene of interest in keratinocyte andepithelial in transgenic mice, contains an expression cassette flankedby about 3 Kb human keratin specific K14 promoter.

About one microliter of ligation reaction was electroporated into DH10BElectroMax™ competent cells (GIBCO BRL, Gaithersburg, Md.) according tomanufacturer's direction and plated onto LB plates containing 100 μg/mlampicillin, and incubated overnight. Colonies were picked and grown inLB media containing 100 μg/ml ampicillin. Miniprep DNA was prepared fromthe picked clones and screened for the murine IL-20 insert byrestriction digestion FseI and AscI combined, and subsequent agarose gelelectrophoresis. The TG construct with correct cDNA inserts wereconfirmed by sequencing analysis. Maxipreps of the correct pRSK14-murineIL-20 were performed.

b). Generation and Characterization of K14 IL-20 Transgenic Mice.

A NotI fragment of about 4 Kb in length was isolated from the transgenic(TG) vector containing 5′ and 3′ flanking sequences of the keratinspecific K14 promoter, mouse IL-20 (SEQ ID NO:33; polypeptide shown inSEQ ID NO:34), the Gormon intron, IL-20 cDNA and the human growthhormone polyA signal sequences. It was used for microinjection intofertilized B6C3f1 (Taconic, Germantown, N.Y.) murine oocytes.Microinjection and production of transgenic mice were produced asdescribed in Hogan, B. et al. Manipulating the Mouse Embryo, 2^(nd) ed.,Cold Spring Harbor Laboratory Press, NY, 1994.

A TAQMAN™ RT-PCR reaction was used to quantitate expression of TG RNA byusing PCR primers specific to the human growth hormone polyA signalportion of the transgene.

All TG constructs expressing IL-20 exhibit a high rate of paranatalmortality, and the TG pups that were born typically exhibits a “shiny”phenotype. The shiny appearance of the neonate pups appeared to beassociated with a stiffening of the skin, as if they were drying out,resulting in a reduction of proper nursing. Their movements becomestiffened in general. HistoPathologically the shiny pups have athickened epidermis and the keratin layer was compacted. Most of theseshiny founder pups died within the first 5 days, and the surviving andweaned pups were in general not expressing the transgene (per transcriptanalysis), or they were chimeric (per low transmittion of the transgeneto the offspring).

One line expressing murine IL-20, driven by the K14 promotor, wasestablished. The expression level in the skin and the thymus was low,and all the neonates were born with a shiny phenotype. In general thisline had 20% TG offspring, indicating 50-60% of the transgenic pups diein utero. (In a Hemizygous mating 50% of the offspring should be TG.)

2. Generation of Mice with Ablated IL-22RA Expression: IL-22RA KnockoutMice

a). Generation of Knockout (KO) Construct for Murine IL-22RA.

To further study biological function of IL-22RA in vivo, a mouseKnockout (KO) strain was created to ablate IL-22RA expression. First,Mouse IL-22RA cDNA probes were used to screen a mouse 129/SvJ genomicBAC library. Clones containing IL-22RA genomic locus were identified andcharacterized. Murine IL-22RA polynucleotide is shown in SEQ ID NO:41and polypeptide in SEQ ID NO:42.

To create a knockout construct for ablation of IL-22RA, a Knockoutvector was made by using ET cloning technique (Zhang et al. 1998. A newlogic for DNA engineering using recombination in E. coli. Nat. Genet.Vol. 20:123-8). Briefly, the KO vector contains a 1.8 kb 5′ arm (shortarm), an IRES-LacZ/MC1neo Selectable marker, and a 10 Kb 3′ arm (longarm) of IL-22RA gene. In the KO vector, exons 2, 3 and 4 as well asIntrons 2 and 3 of IL-22RA genomic sequence were replace by theIRES-LacZ/MC1neo Selectable marker so that a deletion of about 4.4 Kbwas generated by homologous recombination in ES cells.

After linearization of the KO vector by restriction enzyme PmeI, it waselectroporated into 129/SvJ ES cells. Selection of homologousrecombination events, as well as identification of recombinant ES cloneswere performed as described in Robertson, E. J. et al. Teratocarcinomasand Embryonic Stem Cells: A Practical Approach, 2^(nd) ed., IRL PressLimited, Oxford, 1987.

b). Creation and Analysis of Mice with Ablated IL-22RA Expression.

Positive ES clones, in which deletion of Exons 2-4 and Introns 2-3 ofIL-22RA genomic locus occurs, were expanded. They were injected intobalstocysts of C57B1/6j mice. After brief re-expansion of the injectedblastocysts, they were introduced into pseudo-pregnant foster mothers togenerate chimeras. Blastocyst injection, chimera breeding and subsequentgermline transmission of mutated IL-22—RA were performed as described inRobertson, E. J. et al. Teratocarcinomas and Embryonic Stem Cells: APractical Approach, 2^(nd) ed., IRL Press Limited, Oxford, 1987.

The KO mutant mice were identified by PCR genotyping strategy. Three PCRprimers, ZC22901 (SEQ ID NO:35), ZC45039 ((SEQ ID NO:36), ZC38573 (SEQID NO:37) were used in a multiplex PCR reaction to detect wild-typeallele and mutant allele. The wild-type (WT) allele yields a DNAfragment of 229 bp in length, while the mutant allele generates a DNAfragment of 371 bp in length.

The pairing of Hemizygote mice produce a normal ratio of Homozygote(HOM), Heterozygote (Het), and wild type (WT) offspring, as well as anormal sex ratio. Inspecting the mice through a PhysioScreen (Collectingbody weight, tissue weight, complete blood count (CBC), clinicalchemistry, gross observation, and HistoPathology) revealed no apparentdifferences between HOM, Het, and WT animals.

B. IL-22RA was Necessary for IL-22 Induced SAA: SAA ELISA Showing SAAExpression Induced by IL-22 was Absent in IL-22RA Knockout Mice:

To assess whether IL-22RA was necessary for SAA induction in miceinjected with IL-22, IL-22RA KO mice were injected with 5 ug IL-22 andbled 6 hr later.

An Elisa to determine SAA levels in the serum samples was performedusing the Mouse SAA Immunoassay Kit (BioSource International,California) following the manufacturer's directions, with the serumdiluted 1:1000. Four out of five WT mice showed elevated SAA levels inresponse to IL-22 injection, while four out of five HOM IL-22RA KO miceshowed basal levels of SAA. Both Het IL-22RA KO mice tested haveelevated SAA levels, but lower than the SAA levels in the elevated WTmice. This indicates that IL-22RA was necessary for the induction of SAAby IL-22.

These results provided evidence that effectively blocking IL-22RAactivity, for example via an IL-22RA gene knockout or similarly via aneutralizing monoclonal antibody to IL-22RA of the present invention,would similarly reduce IL-22-induced inflammation, for example inpsoriasis, IBD, colitis, endotoxemia, or other inflammatory diseasesinduced by IL-22.

C. IL-22RA was Necessary for IL-22 Induced Epithelial Thickening:Administration of IL-22 Pure Protein Via Osmotic Mini-pump ImplantedSub-cutaneous does not Cause Thickening of the Epidermis in IL-22R KOMice.

To assess whether IL-22RA was necessary for the IL-22 induced epithelialthickening, IL-22 was administered subcutaneously to IL-22RA HOM and WTKO mice via osmotic mini-pumps The pumps delivered IL-22 at a rate of18.4 μL per day for 7 days. Four HOM and 6 WT IL-22RA KO mice receivedIL-22 protein, while 3 HOM and 1 WT received PBS.

Serum samples from IL-22 treated mice were tested in BaF3 proliferationassay to confirm the presence of IL-22. BaF3 cells transfected withIL-22RA and CRF2-4 require the presence of either IL-22 or murine IL3 toproliferate. These cells were spun down and washed in the completemedia, without mIL-3 (RPMI medium (JRH Bioscience Inc., Lenexa, Kans.)supplemented with 10% heat-inactivated fetal calf serum, 2 mML-GLUTAMAX-1™ (Gibco BRL), 1 mM Sodium Pyruvate (Gibco BRL), and PSNantibiotics (GIBCO BRL)) (hereinafter referred to as “mIL-3 freemedia”). The cells were spun and washed 3 times to ensure the removal ofmIL-3. Cells were then counted in a hemacytometer and plated in a96-well format at 5000 cells per well in a final volume of 200 ul perwell using the mIL-3 free media. Mouse serum was present in the wells at1%, 0.5%, 0.25% or 0.125%. The assay plates were incubated at 37° C., 5%CO₂ for 3 days at which time Alamar Blue (Accumed, Chicago, Ill.) wasadded at 20 μl/well. Plates were again incubated at 37° C., 5% CO₂ for24 hours. Alamar Blue gives a fluorometric readout based on number oflive cells, and was thus a direct measurement of cell proliferation incomparison to a negative control. Plates were again incubated at 37° C.,5% CO₂ for 24 hours. Plates were read on the Wallac Victor 2 1420Multilabel Counter (Wallac, Turku, Finland) at wavelengths 530(Excitation) and 590 (Emission). Results showed none of the PBS injectedanimals had IL-22 activity, while 1 of 1 Het animals, 2 of 4 HOManimals, and 3 of 6 WT animals had detectable IL-22 activity.Proliferation induced by this serum was blocked by the presence of 1ug/ml IL-22BP, proving that it was IL-22 specific.

Skin samples from IL-22 treated and untreated IL-22RA HOM and Hetknockout (KO) and WT control mice were immersion fixed in 10% bufferedformalin. The tissues were trimmed and embedded in paraffin, routinelyprocessed, sectioned at 5 μm (Jung 2065 Supercut microtome, LeicaMicrosystems, Wetzlar, Germany) and stained with H&E. The stainedtissues were evaluated under a light microscope (Nikon Eclipse E600,Nikon Inc., Melville, N.Y.) by an ACVP board certified veterinarypathologist.

Each skin sample was evaluated on a 0 (none) to 4 (severe) scale forseverity of inflammation in the tissue bordering the pump implantationsite in the hypodermis, on a 0 (none) to 3 (diffuse) scale for extent ofepidermal thickening (acanthosis), and the number of epithelial layerswere counted in the thickest part of the epidermis. No difference wasfound between the HOM mice and the WT mice that had been given PBS. Theresults from these two groups were pooled into one PBS group. The meanand standard deviation was determined for each treatment group and wasshown in Table 14 below.

TABLE 14 HOM KO: Treatment PBS control IL-22 WT: IL-22 Number of mice 44 6 Epithelial thickness 3.5 ± 1.0 3.2 ± 0.5 5.9 ± 2.3 Extent ofacanthosis 0.5 ± 1.0 0.2 ± 0.5 1.9 ± 1.3 Inflammation 1.5 ± 1.0 1.2 ±1.0 2.0 ± 1.0

Results showed a trend toward increased epithelial thickness andacanthosis in WT mice treated with IL-22 and less epithelial thicknessand acanthosis in IL-22RA HOM mice when exposed to IL-22.

These results provide evidence that effectively blocking IL-22RAactivity, for example via an IL-22RA gene knockout or similarly via aneutralizing monoclonal antibody to IL-22RA of the present invention,would similarly reduce IL-22-induced skin effects, for example inpsoriasis, IBD, colitis, or other inflammatory diseases induced byIL-22.

D. IL-22RA was Necessary for IL-20 Induced Shine of Neonate Pups Skin:Crossbreeding of Transgenic Mice Expressing Murine IL-20 with IL-22RA KOMice Produce Transgenic Pups that do not Shine

To assess whether IL-22RA was necessary for the IL-20 induced shine ofneonate TG pups, the K14 muIL-20 transgene was crossed into the IL-22RAKO line, and the neonates were observed for the shiny phenotype.

Sixty-nine pups have been born with a Mendelian genotype ratio. All theTG on a Het KO background were shiny, while none of the non-TG, nor theTG on the HOM KO background were shiny.

An alamar blue proliferation assay using BaF3 cells expressing IL-20RAand IL-20RB was performed to assess the presence of IL-20 in the mouseserum. These cells will proliferate in response to either IL-20 ormurine IL3. Procedure was the same as the one described in Section C,above. Results of the assay showed that all the TG mice had comparableIL-20 activity, and at the same level as IL-20 TG on the C57BL/6Nbackground. The absence of any shiny neonate phenotype indicate thatskinny neonate phenotype was dependent on the presence of IL-22RA. Theproliferation assay showed that all the TG mice had comparable IL-20activity, and at the same level as IL-20 TG on the C57BL/6N background.The absence of any shiny neonate phenotype indicate that skinny neonatephenotype was dependent on the presence of IL-22RA.

On day three post partum, pups from litters containing K14 muIL-20 TG onthe IL-22RA KO background were humanely euthanized and the whole bodyimmersion fixed in 10% buffered formalin. The fixed tissues were trimmedinto cross-sections of the thorax and abdomen, embedded in paraffin,routinely processed, sectioned at 5 um (Jung 2065 Supercut microtome,Leica Microsystems, Wetzlar, Germany) and stained with H&E. The stainedtissues were evaluated under a light microscope (Nikon Eclipse E600,Nikon Inc., Melville, N.Y.) in blinded fashion by an ACVP boardcertified veterinary pathologist. Tissue abnormalities were noted andthe number of epithelial layers in the epidermis of the dorsal anteriorthorax counted.

Tissues from three IL-20 TG on HOM IL-22RA KO background (IL-20TG/IL-22RA KO HOM) and three non-TG on IL-22RRA HOM KO background(non-TG/IL-22RA KO HOM) mice were microscopically examined and found tocontain no abnormalities. Tissues from two IL-20 TG on Het IL-22RA KObackground (IL-20 TG/IL-22RA KO Het) mice were also examined. Thenumbers of epithelial layers in the epidermis was similar in allanimals. However, the epidermis of the two IL-20 TG/IL-22RA KO Het micewas hypereosinophilic as compared to the other animals and exhibitedloss of granularity in the stratum granulosum. No other abnormalitieswere noted in the skin or other tissues of any of the mice.

These results provide evidence that effectively blocking IL-22RAactivity, for example via an IL-22RA gene knockout or similarly via aneutralizing monoclonal antibody to IL-22RA of the present invention,would similarly reduce IL-20-induced skin effects, as well asIL-22-induced skin effects, for example in psoriasis, IBD, colitis, orother inflammatory diseases induced by IL-20, and or IL-22 includingIBD, arthritis, asthma, psoriatic arthritis, colitis, inflammatory skinconditions, and atopic dermatitis.

EXAMPLE 33 Histomorphometric Image Analysis of IL-22RA Knockout Mice

A line of k14 IL-20 m transgenic (TG) mice has been established, and theTG neonates exhibit a shiny phenotype. The transgene is expressed by thek14 promoter, which directs expression to the keratin producing cells inthe skin. A line of IL-22RA knock out (KO) mice has also beenestablished, and no significant changes have been observed in theun-challenged mice. The two lines were crossed together and neonateswere collected having the following four different genotypes: (1)TG/-HOM: expressing the k14 IL-20 m transgene on a background notexpressing IL-22RA; (2) TG/-Het: expressing the k14 IL-20 m transgene ona background expressing some IL-22RA from one copy of the IL-22RA gene;(3) WT/HOM: not expressing the k14 IL-20 m transgene on a background notexpressing IL-22RA; and (4) WT/Het: not expressing the k14 IL-20 mtransgene on a background expressing some IL-22RA from one copy of theIL-22RA gene. Thirty-four neonate pups of these various genotypes wereeuthanized at day 3, approximately 48 hours post partum (Table 15):

TABLE 15 TG/- HOM* TG/- Het* WT/HOM* WT/Het* (Group1) (Group 2) (Group3) (Group 4) Total n = 10 n = 10 n = 9 n = 5 TG = transgenic; WT = wildtype; HOM = homozygous; Het = heterozygous; and n = number of pups.

Each pup was transversely cut into three sections (cranial thorax,caudal thorax and abdomen) through the body and the head was discarded.The tissue specimens, 4.0-5.0 mm in thickness, were fixed in 10% neutralbuffered formalin, processed into paraffin blocks and stained withhematoxylin and eosin (H&E) for routine histological examination andhistomorphometric image analysis. Epidermis from the dorsal area ofspinal cord in each tissue sample was chosen for histomorphometric imageanalysis using an Olympus BH-2 microscope, a video camera (Dage-MTI,Michigan City, Ind.) and BioQuant True Color windows 98 software (R&MBiometrics, Inc. Nashville, Tenn. 37209) with the following set up:Parameter: mag. 10X, Z off set 0; Array: length (m); Measure: manual andadditive mode. The thickness (μm) of epidermis and stratum corneum orcornified layer from each skin sample were individually measured 10times, with about 0.1 mm interval between each measurement, in each 10×microscopic field and the mean value, SD and SEM were obtained by Excelcalculation. All of the sections were randomized and measured in ablinded fashion. After the measurement, the sections were unblinded, andthe results matched to treatment groups. Final results by treatmentgroup were classified as follows: 1. Average epidermal thickness (μm) incranial thorax, caudal thorax and abdomen, and then sub-classified as(a) Average epidermal thickness in cranial thorax; (b) Average epidermalthickness in caudal thorax; and (c) Average epidermal thickness inabdomen. 2. Average thickness of stratum corneum (μm) in cranial thorax,caudal thorax and abdomen, and sub-classified as (a) Average thicknessof stratum corneum in cranial thorax; (b) Average thickness of stratumcorneum in caudal thorax; and (c) Average thickness of stratum corneumin abdomen. 3. Average thickness of epidermis plus stratum corneum incranial thorax, caudal thorax and abdomen. The resulting data wasanalyzed using GraphPad InStat software (GraphPad Software, Inc., SanDiego, Calif. 92121). One-way analysis of variance (ANOVA) was appliedto examine the statistical significance of differences in mean valuesfrom group1 to group 4. Tukey-Kramer Multiple Comparisons Test was usedfor the determination of statistical differences in mean values betweentwo groups (*P<0.05; **P<0.01; ***P<0.001; ****P<0.0001). Observationsof P<0.05 were considered significant.

(1) Histomorphometric Results

(a) Average Epidermal Thickness (μm) in Cranial Thorax, Caudal Thoraxand Abdomen

Epidermal thickness increased significantly in IL-20 transgenic pupslacking one copy of the IL-22RA gene (TG/-Het) versus the IL-20transgenic pups with no expression of IL-22RA (TG/-HOM, P=0.001***) andversus the control littermates (WT/HOM, P=0.001*** and WT/Het,P=0.001***), respectively (Table 16). The TG/-Het pups showed increasedthickness of non-keratinized epidermis possibly due to keratinocytehypertrophy. This increase might involve all three nonkeratinized layers(basal, prickle, and granular) but most often affected the prickle celllayer. The epidermis of the TG/-Het pup increased about 25% in thicknessand the prickle became prominent. Whereas the epidermis of TG/-HOM pupswere slightly thicker than the controls (WT/HOM and WT/Het) andstatistics indicated no significant difference between the groups(P>0.05). The epidermal thickness in cranial thorax, caudal thorax andabdomen were also compared. The normally thin epidermis of the abdomenis thicker than caudal thorax and the caudal thorax is thicker than thecranial thorax (Table 16).

TABLE 16 TG/- HOM TG/- Het WT/HOM WT/Het (N = 28) (N = 30) (N = 27) (N =15) Mean 32.58 ± 1.25 41.05 ± 2.04 31.31 ± 1.08 30.83 ± 1.43 Resultsrepresent mean values ± SEM. N = number of sections measured.

The squamous epithelium of the skin in the cranial thorax from theTG/-Het pups showed increase in thickness accompanied by hypertrophy ofthe epidermal cells (keratinocytes); however there was no statisticaldifference compared with other groups, the TG/-HOM, WT/HOM and WT/Het(P=0.1565, Table 17). This seems to result from either histologicalartifact, e.g., section-to-section variability, the nature architectureof the epidermis, or there was not much effect in the thin skin in thecranial thorax. Note: the histology procedure or tissue section of thecranial thorax might disqualify for histomorphometric analysis to obtainstatistical significance.

TABLE 17 TG/- HOM TG/- Het WT/HOM WT/Het (N = 10) (N = 10) (N = 9) (N =5) Mean 29.18 ± 2.24 33.20 ± 2.24 27.28 ± 0.62 29.38 ± 1.77 Resultsrepresent mean values ± SEM. N = number of sections measured

The IL-20 (TG/-) with one copy of the IL-22RA gene (Het) showedincreased mean value of the epidermal thickness compared to the TG/-HOM(P<0.05*), WT/HOM (P<0.001***), and WT/Het (P<0.01*), respectively(Table 18). Statistics indicated extremely significant among the groups(P<0.0001****). The TG/-Het epidermis increased about 29% than that ofWT/Het. The phenotype of IL-20 (TG/-) pups with absence of IL-22RA (HOM)in part resembled to that of the pups lacking one copy of the IL-22RAgene (Het) associated with thicker epidermis than that of the controllittermates (WT/HOM and WT/Het), however, it demonstrated no statisticaldifference compared to the controls (P>0.05). The TG/-HOM epidermisincreased about 14% than that of WT/HOM. Unlike the IL-20 TG/-pups, theIL-22RAm receptor-deficient pups (WT/HOM and WT/Het) demonstratedrelatively thinner epidermal thickness. Noticeably, thehistomorphometric result of epidermal thickness in caudal thorax was aconsistent finding correlated to the average epidermal thickness in thecranial thorax, caudal thorax and abdomen (Table 15), which indicatedthat the histological procedure and tissue section of the caudal thoraxcarried out the best quality for histomorphometric image analysis.

TABLE 18 TG/- HOM TG/- Het WT/HOM WT/Het (N = 10) (N = 10) (N = 9) (N =5) Mean 35.91 ± 1.37 43.79 ± 2.35 30.83 ± 1.86 30.94 ± 2.83 Resultsrepresent mean values ± SEM. N = number of sections measured.

The results of average epidermal thickness in abdomen (Table 19) weresimilar to that in the caudal thorax (Table 18) except that the TG/-HOMshowed no differences compared to the control littermates (WT/HOM andWT/Het, P>0.05). There were some variations in the tissue sections andalso two sections were missing, i.e. without epidermis covering thedorsal area in the TG/-HOM group.

TABLE 19 TG/- HOM TG/- Het WT/HOM WT/Het (N = 8) (N = 10) (N = 9) (N =5) Mean 32.35 ± 1.44 46.33 ± 3.10 35.81 ± 1.90 32.16 ± 2.97 Resultsrepresent mean values ± SEM. N = number of sections measured.(b) Average Thickness (μm) of Stratum Corneum in Cranial Thorax, CaudalThorax and Abdomen

Despite the increased epidermal thickness in the IL-20 transgenic pups(TG/-) on a background either not expressing IL-22RA (HOM) or expressingone copy of the gene (Het), predominate reduction of stratum corneum orcornified layer thickness was observed in the TG/-HOM and TG/-Het skinscompared to the control littermates (WT/HOM and WT/Het) and statisticsindicated extremely significant among the groups (P<0.0001****, Table20). The TG/-Het pups showed about 36%, 50% and 49% decreased amounts ofkeratin on the surface of the epidermis versus the TG/-HOM (P<0.01**),WT/HOM (P<0.001***) and WT/Het (P<0.001***), respectively. The TG/-HOMpups showed about 22% significant reduction in the stratum corneumthickness compared with its control (WT/HOM, P<0.05*) and only 17%reduction versus the WT/Het that revealed no statistical significance(P>0.05). The thickness of stratum corneum in the control pups, WT/HOMand WT/Het were about the same. Apparently, the stratum corneum in thecaudal thorax is thicker than that in the abdomen and the abdomen isthicker than that in the cranial thorax.

TABLE 20 TG/- HOM TG/- Het WT/HOM WT/Het (N = 8) (N = 10) (N = 9) (N =5) Mean 33.26 ± 2.69 21.41 ± 1.27 42.54 ± 2.01 40.31 ± 3.82 Resultsrepresent mean values ± SEM. N = number of sections measured.

The average thickness of stratum corneum in the cranial thorax (Table21) resembled to that in the cranial thorax, caudal thorax and abdomen(Table 20), however significant reduction of stratum corneun was onlyfound in the TG/-Het vs. TG/-HOM (P<0.05*) and vs. WT/HOM (P<0.01**),respectively. The standard deviation and standard error of the mean werehigh which might be due to poor section, missing skin samples, naturearchitecture of the epidermis, or there was not much effect in thecranial thorax. Note: the histology procedure or tissue section of thecranial thorax might disqualify for histomorphometric analysis in orderto obtain quality result.

TABLE 21 TG/- HOM TG/- Het WT/HOM WT/Het (N = 28) (N = 30) (N = 26) (N =14) Mean 34.96 ± 3.53 18.14 ± 3.99 40.47 ± 4.38 32.96 ± 8.11 Resultsrepresent mean values ± SEM. N = number of sections measured

The result of average thickness of stratum corneum in the caudal thorax(Table 22) was similar to that in the cranial thorax, caudal thorax andabdomen but with three exceptions: (1) TG/-HOM vs. TG/-Het and TG/-HOMvs. WT/HOM showed no statistical differences (P>0.05); (2) TG/-HOM vs.WT/Het showed significant difference (P<0.01**); (3) The stratum corneumin the WT/Het remarkably thickened which might be the consequence oftissue processing artifact, e.g., the keratin swelled or expanded whenplaced it in hypotonic solution or left in the water bath too long.

TABLE 22 TG/- HOM TG/- Het WT/HOM WT/Het (N = 10) (N = 10) (N = 8) (N =4) Mean 35.64 ± 3.4 24.22 ± 1.54 44.35 ± 3.51 53.77 ± 7.21 Resultsrepresent mean values ± SEM. N = number of sections measured.

Only the TG/-HOM vs. WT/HOM and TG/-Het vs. WT/HOM showed statisticalsignificant difference, P<0.05* and P<0.001***, respectively (Table 23).The TG/-pups displayed a reduction in the thickness of stratum corneumin the abdomen compared to its control littermates (WT/HOM and WT/Het).

TABLE 23 TG/- HOM TG/- Het WT/HOM WT/Het (N = 8) (N = 10) (N = 9) (N =4) Mean 28.84 ± 4.36 21.86 ± 1.30 42.45 ± 3.15 33.25 ± 3.96 Resultsrepresent mean values ± SEM. N = number of sections measured(c) Average Thickness (μm) of Epidermis Plus Stratum Corneum in CranialThorax, Caudal Thorax and Abdomen

TG/-Het pups displayed a significant increase in the epidermal thicknessand a significant decrease in the thickness of stratum corneum comparedwith the control littermates (WT/HOM and WT/Het) and the TG/-HOM pupsproduced a similar result but with a minimal effect (Table 24).

TABLE 24 TG/- HOM TG/- Het WT/HOM WT/Het (N = 10) (N = 10) (N = 9) (N =4) Stratum corneum 32.58 41.05 31.31 30.83 Epidermis 33.26 21.41 42.5440.31 Results represent mean values. N = number of pups(d) Signaling of IL-20 Through Both IL-20RA and IL-22RA

The epidermis is a stratified, continually renewing epithelium dependenton a balance among cell proliferation, differentiation, and death forhomeostasis. In normal epidermis, a mitotically active basal layer givesrise to terminally differentiating keratinocytes that migrate outwardand are ultimately sloughed from the skin surface as enucleated squames,the keratin or cornified layer located in the stratum corneum. Althoughmany proteins are known to function in maintaining epidermalhomeostasis, the molecular coordination of these events is poorlyunderstood. IL-20 is a novel receptor-interacting protein and it signalsthrough either IL20RA or IL-22RA receptors (IL-22RA) expressed in alayer of skin associated with the proliferation of keratinocytes. IL-20transgenic neonates display abnormal thickened and shiny skin phenotype.IL-22RAm (HOM) deficiency in mice showed no response to IL-22 treatment,whereas wild type mice with the IL-22RA gene and treated with IL-22demonstrated significant increase in the epidermal thickness(P<0.001***, see the results in IL-22RAm KO/IL-22 histomorphometricimage analysis, PID 59.2). To investigate whether the absence of IL-22RAhas an effect on the shiny phenotype observed in the K14 IL-20m TGneonates, transgenic mice ectopically expressing IL-20 were mated withIL-22RA homozygous (HOM) or IL-22RA heterozygous (Het) deficient. Aquantitative image analysis of epidermal thickness was previouslyperformed on fewer pups in the caudal thorax from this study (i.e. 19pups, 1 section per pup, for a total of 19 sections) but no statisticalsignificance was obtained due to the limited number of animals studiedand the variation within the groups. The aim of the present study was tohistomorphometrically quantitate more skin samples in cranial thorax,caudal thorax and abdomen from each pup from the same study (i.e. 34pups, 3 section per pup, for a total of 102 sections) to explore thebiology of IL-20 and obtain reliable quantitative results. For effectiveimage analysis, we made sure that the orientation of the skin in theparaffin block was consistent and the skin samples were measured fromthe same respective locations in all individual and groups of pups. Twokinds of measurements were performed: (1) The thickness of epidermis wasmeasured 10 times per 10× microscopic field in each skin sample, each atthe dorsal side of spinal cord, to investigate the role of IL-20 inmediating keratinocyte proliferation and differentiation; (2) Thethickness of cornified layer or the stratum corneum was measured in thesame manner to correlate the results with the shiny skin appearance inthe IL-20 TG neonates.

Histomorphometric image analysis of the epidermal thickness revealedthat the TG/-Het neonates, expressing the k14 IL-20m transgene on abackground expressing some IL-22RA from one copy of the IL-22RA genedisplayed thickened epidermis and the TG/-HOM neonates, expressing thek14 IL-20m transgene on a background not expressing IL-22RA had nosignificant change. The epidermal thickness increased significantly inIL-20 transgenic pups lacking one copy of the IL-22RA gene (TG/-Het)versus the IL-20 transgenic pups lacking both copy of the IL-22RA genes(TG/-HOM, P=0.001***) and versus the control littermates (WT/HOM,P=0.001*** and WT/Het, P=0.001***). The TG/-Het pups showed increasedthickness of the non-keratinized epidermis mainly due to hypertrophy ofthe keratinocytes in the prickle layer. The epidermis of the TG/-Het pupincreased about 25% in thickness, whereas the epidermis of TG/-HOM pupswere only slightly thicker, increased about 4-5%, than the controls(WT/HOM and WT/Het) and statistics indicated no significant differencebetween the TG/-HOM and its control WT/HOM (P>0.05).

Histomorphometric results of the stratum corneum showed that despite theepidermal thickening in the TG/-Het neonates, predominate reduction ofkeratin or cornified layer thickness was observed in TG/-HOM and TG/-Hetskins compared to the control littermates (WT/HOM and WT/Het) andstatistics indicated extremely significant among the groups(P<0.0001****). The TG/-Het pups showed about 36%, 50% and 49% decreasedamounts of keratin on the surface of the epidermis versus the TG/-HOM(P<0.01**), WT/HOM (P<0.001***) and WT/Het (P<0.001***), respectively.The TG/-HOM pups showed about 22% significant reduction in the stratumcorneum thickness compared to its control (WT/HOM, P<0.05*) and only 17%reduction versus the WT/Het (P>0.05). The thickness of stratum corneumin the control pups, WT/HOM and WT/Het were about the same. Thereduction in average thickness of stratum corneum in the TG/-HOM andTG/-Het neonates seemed to correlate the gross finding at sac, in whichat gross level the IL-20 (TG)/IL-22RA (Het) neonates appear to havereduced shine (e.g., with less keratin), called a sheen, while the IL-20(TG)/IL-22RA (HOM) neonates do not shine (e.g., with more keratin).Histologically, the keratin in the stratum corneum in the TG/-pupsappeared to be more compact than that in the WT pups. Together, thethickened epidermis associated with hypertrophic keratinocytes and thethin layer of stratum corneum in the IL-20 transgenic neonates mightexplain why they displayed shiny skin phenotype.

Increased hypertrophy and disturbed terminal differentiation ofkeratinocytes were observed in the IL-20 transgenic neonates with atargeted knock out of one copy of the IL-22RA gene (Het). The skinexhibited hypertrophy in keratinocytes but fails fully differentiate,lacking keratin or the stratum corneum. The IL-20 transgenic neonateswith disruption of two copy of the IL-22RA genes (HOM) displayed aphenotype that resembled the TG/-Het skin but showed less or minimaleffect (FIGS. 12-15). It seems that the absence of IL-22RA (HOM) has apartial effect on the shiny phenotype observed in the K14 IL-20m TGneonates and the absence of IL-22RA (Het) has minimal or no effect onthe shiny phenotype. In other words, the signaling of IL-20, a novelreceptor-interacting protein which signals through either IL-20RA orIL-22RA receptor (IL-22RA) is probably not obstructed by deficientexpression of one copy of the IL-22RA gene (Het) but is partiallyobstructed by deficient expression of two copies of the IL-22RA gene(HOM).

These results provide evidence that effectively blocking IL-22RAactivity, for example via an IL-22RA gene knockout or similarly via aneutralizing monoclonal antibody to IL-22RA of the present invention,would similarly reduce IL-20-induced skin effects, as well asIL-22-induced skin effects, for example in psoriasis, IBD, colitis, orother inflammatory diseases induced by IL-20, and or IL-22.

EXAMPLE 34 Effect of IL-22 on IL-22RA Knock Out Mice

Thirty-six mice including 23 IL-22RA KO (HOM) and 13 controls (WT) weretreated with either IL-22 or PBS administered subcutaneously byimplanted a minipump with tube or a minipump alone (Table 25):

TABLE 25 HOM/PBS HOM/IL-22 WT/PBS WT/IL-22 (Group1) (Group 2) (Group 3)(Group 4) Male n = 3 n = 10 n = 3 n = 8 Female n = 0 n = 10 n = 0 n = 2Total n = 3 n = 20 n = 3 n = 10

Skin sample, 1.5-2.5 cm in length and 4.0-5.0 mm in thickness, from thepumping site of each animal was obtained for routine histologicalexamination and histomorphometric image analysis. All tissue specimenswere fixed in 10% neutral buffered formalin and processed into paraffinblocks. Six segmental sections, 5 um in thickness and 10 um intervalbetween adjacent sections with epithelium covering the entire surface,from each skin sample per animal were stained with hematoxylin and eosin(H&E). Histomorphometric image analysis of the skin samples wasperformed using an Olympus BH-2 microscope, a video camera (Dage-MTI,Michigan City, Ind.) and BioQuant True Color windows 98 software (R&MBiometrics, Inc. Nashville, Tenn. 37209) with the was following set up:Parameter: mag. 10X, Z off set 0; Array: length (um); Measure: manualand additive mode. The thickness (um) of epidermis was measured 5 timesin each 10× microscopic field from a total of 4 fields captured from thecenter 0.4 cm of each skin section (e.g., one 10× microscopic field=0.1cm and four 10× microscopic fields=0.4 cm). Total of 6 sections fromeach animal were measured and the mean value, SD and SEM were obtainedby Excel calculation. All of the sections were randomized and measuredin a blinded fashion. After the measurement, the sections wereunblended, and the results matched to treatment groups. Final results bytreatment group were classified as follows: 1. Epidermal thickness fromHOM and WT male and female mice. 2. Epidermal thickness from HOM and WTmale mice. The resulting data was analyzed using GraphPad InStatsoftware (GraphPad Software, Inc., San Diego, Calif. 92121). One-wayanalysis of variance (ANOVA) was applied to examine the statisticalsignificance of differences in mean values from group 1 to group 4.Tukey-Kramer Multiple Comparisons Test and Unpaired-T test were appliedto analyze the significance in mean values between two groups.Observations of P<0.05 were considered significant.

III. Histomorphometric Results (1) Epidermal Thickness (μm) from HOM andWT Male and Female Mice

Epidermal thickness increased significantly in the WT mouse skinstreated with IL-22 (WT/IL-22) versus the WT/PBS controls (P=0.0001).IL-22RAm KO mouse skin treated with IL-22 (HOM/IL-22) showed increasedmean value of the epidermal thickness compared with the HOM/PBScontrols, however statistics indicated no significant difference betweenthe two groups (P>0.05). Predominate reduction of epidermal thicknesswas observed in the IL-22RA KO mice compared with the WT mice (e.g.,HOM/IL-22 vs. WT/IL-22: P<0.001) (Table 26).

TABLE 26 HOM/PBS HOM/IL-22 WT/PBS WT/IL-22 (N = 3) (N = 19) (N = 3) (N =10) Mean 14.15 ± 0.19 19.01 ± 1.03 23.34 ± 5.49 43.08 ± 1.85 Resultsrepresent mean values ± SEM. N = animal number.(2) Epidermal Thickness (um) from HOM and WT Male Mice

Epidermal thickness increased about 2-fold in the WT male mouse skinstreated with IL-22 (WT/IL-22) when compared with WT/PBS male controls(P=0.0001), however, IL-22RAm KO male mouse epidermis treated with IL-22(HOM/IL-22) only showed slightly increase compared with the HOM/PBS malecontrols (P>0.05). Noticeably, IL-22RAm KO mice exhibited markedreduction of epidermal thickness when compared with its control, the WTmale mice (e.g., HOM/PBS VS WT/PBS: P<0.05; HOM/IL-22 VS WT/IL-22:P<0.001) (Table 27).

TABLE 27 HOM/PBS HOM/IL-22 WT/PBS WT/IL-22 (N = 3) (N = 9) (N = 3) (N =8) Mean 14.15 ± 0.19 15.86 ± 0.75 23.34 ± 5.49 41.41 ± 1.71 Resultsrepresent mean values ± SEM.(3) Epidermal Thickness (um) from HOM and WT Mice, Male vs. Female

Epidermis of the female mice was found thicker than that of the malemice (e.g., HOM/IL-22/male VS HOM/IL-22/female: P<0.01; WT/IL-22/male VSWT/IL-22/female: P<0.05) (Table 28).

TABLE 28 HOM/IL-22 HOM/IL-22 (Female, WT/IL-22 WT/IL-22 (Male, N = 9) N= 10) (Male, N = 8) (Female, N = 2) Mean 15.86 ± 0.75 21.85 ± 1.3 41.41± 1.71 49.75 ± 4.82 Results represent mean values ± SEM.(4) Epidermal Thickness (μm) from HOM Mice, IL-22 Pump vs. IL-22 Pumpwith Tube

Epidermis from IL-22RAm KO (HOM) mice with IL-22 pump & tube were foundsignificantly thicker than that of the IL-22RAm KO (HOM) mice with pumponly (P<0.0001, by unpaired-T test) (Table 29).

TABLE 29 HOM w/IL-22 pump HOM w/IL-22 pump with tube (M = 8 & F = 2, N =10) (M = 2 & F = 8, N = 10) Mean 15.85 + 0.65 23.30 + 1.36 Resultsrepresent mean values ± SEM. M: male; F: female; N: total number ofmice.IV. Discussion:

Taken together, the aim of this study is to characterize the epidermaleffects in the IL-22 treated skins from both IL-22RAm KO and WT mice andrelates these findings to clinical indications. A quantitative imageanalysis was performed to determine the thickness of the epidermis inH&E stained skin sections. The skin samples from each animal werehistomorphometrically measured 120 times (i.e. 20 times/each section X 6segmental sections from each mouse=120 measurements) and the averageepidermal thickness was obtained by Excel calculation. Histomorphometricstudy demonstrated that IL-22 resulted in significant increase in theepidermal thickness especially in the WT mice with presence of theIL-22RA receptor (P<0.0001 by ANOVA, considered extremely significant)and showed less or minimal effects on the IL-22RAm KO (HOM) mice withabsence of the IL-22RA receptor (P>0.05). The epidermal thickness in theIL-22 treated WT mice was increased about 43% than that treated with PBS(e.g., WT/PBS, P<0.001), whereas the IL-22 treated IL-22RAm KO (HOM)mice only showed 26% increase in epidermal thickness compared with thecontrol (HOM/PBS, P>0.05). IL-22RAm KO mice exhibited thinner epidermiswhen compared with the WT mice (P<0.001). Overall, the biologic effectsof IL-22 on mouse skin suggest that this factor might be involved in theregulation of epidermal growth and proliferation.

EXAMPLE 35 Pharmacokinetics of an Anti-human IL-20 Monoclonal Antibody(Clone #262.7.1.3.2.4)

The test monoclonal antibody, anti-human IL-20 mAb, (clone#262.7.1.3.2.4) was provided in 3×3 mL aliquots at a concentration of1.08 mg/mL (determined by UV Absorbance at 280 nM) and was stored at−80° C. until use. The vehicle was 1×PBS (50 mM NaPO4, 109 mM NaCl), pH7.3. The mAb was thawed at room temperature before use and aliquots 1and 2 were used as provided for the 100 μg IV and SC dosing groups,respectively. Half of aliquot 3 was diluted 1:2 in 1×PBS for the 50 μgSC dose group and the second half of aliquot 3 was diluted 1:10 in 1×PBSfor the 10 μg SC dose group. Female SCID mice (n=96), were received fromCharles River Labs. Animals were checked for health on arrival andgroup-housed (3 animals per cage). The mice were 12 weeks old with anaverage body weight of 22 g at the beginning of the study.

A. Dosing Protocol

Female SCID mice (n=24/dose group) were randomly placed into four dosinggroups (see Table 30). Group 1 was administered the anti-huIL-20 mAb viaIV injection of approximately 93 μL in a tail vein and Groups 2, 3, and4 were administered the mAb via SC injection of approximately 93 μL inthe scruff of the neck.

B. Sample Collection

Prior to blood collection, mice were fully anesthetized with halothaneor isofluorane. Blood samples were collected via cardiac stick for alltimepoints except the 168 hr timepoint (collected via eye bleed and thesame animals were bled again at the 504 hr timepoint via cardiac stick).Blood was collected into serum separator tubes and allowed to clot for15 minutes. Samples were subsequently centrifuged for 3 minutes at14,000 rpm. Following centrifugation, aliquots of 125-150 uL weredispensed into labeled eppendorf tubes and immediately stored at −80° C.until analysis (Table 30).

TABLE 30 Group # Dose (ROA) Animals PK Timepoints 1 100 μg (IV) 3mice/timepoint* 0.25, 1, 4, 8, 24, 72, 168, 336 and 504 hr 2 100 μg (SC)3 mice/timepoint* 0.25, 1, 4, 8, 24, 72, 168, 336 and 504 hr 3  50 μg(SC) 3 mice/timepoint* 0.25, 1, 4, 8, 24, 72, 168, 336 and 504 hr 4  10μg (SC) 3 mice/timepoint* 0.25, 1, 4, 8, 24, 72, 168, 336 and 504 hr*The same animals were used for the 168 and 504 hr timepoints.C. Quantification of Serum Anti-huIL-20 mAb Concentrations by ELISA

An Enzyme Linked Immunosorbant Assay (ELISA) was developed and qualifiedto analyze mouse serum samples from animals dosed with anti-IL-20 mAb267.7.1.3.2.4 during pharmacokinetic studies. This assay was designed totake advantage of a commercially available secondary antibody andcalorimetric detection using TMB. The dilutions used for the standardcurve were modified to improve the definition of the linear portion ofthe standard curve. A standard curve in the range of 100 ng/mL to 0.231ng/mL with 2-fold dilutions allowed for quantitation of the mouse serumsamples. QC samples were diluted to 1:100, 1:1000 and 1:10000 in 10%SCID mouse serum and back calculated from the standard curve.

D. Pharmacokinetic Analysis

Serum concentration versus time data were downloaded into WinNonlinProfessional 4.0 software (Pharsight, Inc.; Cary, N.C.) forpharmacokinetic analysis. Noncompartmental analysis was used todetermine pharmacokinetic parameters based on the mean data at each timepoint.

E. Results

Mean serum anti-human IL-20 mAb concentrations following administrationof 100 μg IV and 100, 50, and 10 μg SC are shown in Table 31:

TABLE 31 100 μg IV Time Conc 10 μg SC 50 μg SC 100 μg SC (hr) (μg/mL)Conc (μg/mL) Conc (μg/mL) Conc (μg/mL) 0.25 196 (12) LTR  0.101 (0.065) 0.481 (0.485) 1 154 (18) 0.356 (0.146)  1.61 (0.52)  3.48 (1.72) 4 118(20) 2.42 (0.53) 10.4 (3.4) 19.7 (4.7) 8 112 (20) 3.41 (0.30) 18.9 (3.6)40.2 (6.4) 24 103 (13) 4.95 (0.05) 26.3 (0.7) 50.1 (6.2) 72 101 (16)4.27 (0.79) 21.0 (3.4) 43.4 (2.7) 168  45.6 (15.4) 2.92 (0.53) 19.6(2.7) 37.6 (3.4) 336  36.4 (16.6) 3.60 (0.31) 23.5 (3.5) 34.4 (5.8) 50428.8 (3.8) 2.74 (0.39) 20.5 (3.6) 25.7 (2.1) LTR: less than reportable

Following IV administration, the mAb concentration versus time profiledemonstrated a biexponential decline. Following SC administration, themAb appeared to have a slow absorption phase, with absorptionrate-limited elimination. The serum pharmacokinetic parameters based onthe mean data at each time point are shown in Table 32:

TABLE 32 Parameter Units 100 μg IV 10 μg SC 50 μg SC 100 μg SC C₀(IV);C_(max) (SC) μg/mL 212 4.95 26.3 50.1 T_(max) hr N/A 24 24 24t_(1/2, λz) hr 509 ND ND 612 AUC_((0-t)) hr · μg/mL 27059 1730 1084518110 AUC_((0-inf)) hr · μg/mL 48269 ND ND 41561 AUC (% extrapolated) %43.9 ND ND 56.4 V_(ss) (IV); V_(z)/F (SC) mL 1.34 ND ND 2.12 Cl (IV);Cl/F (SC) mL/hr 0.002 ND ND 0.002 F (bioavailability) % N/A ND ND 86.1ND: not determinable due to lack of data in the terminal eliminationphase of the concentration versus time profile

Following IV administration, the mAb demonstrated a very low clearance(C1=0.002 mL/hr) and long elimination half-life (t_(1/2,λz)≈21 days).The mAb demonstrated a steady-state volume of distribution (V_(ss)=1.3mL) that is less than the blood volume in a mouse (≈1.7 mL), suggestingthat the mAb did not distribute substantially out of the vascularcompartment. The back-calculated maximum concentration (C₀) was higherthan expected based on the injected dose and the blood volume in themouse. This, along with the small V_(ss), suggests that the mAb may beconfined, to a large extent, in the serum fraction of the blood.

Following SC administration, C_(max) values increased linearly withdose. At the 100 μg SC dose, the mAb had a t_(1/2, λz) of approximately25 days with clearance and an apparent volume of distribution similar tothat following IV dosing. Bioavailability was 86%. At the lower two SCdoses, most pharmacokinetic parameters could not be estimated due to thelack of a measurable terminal elimination phase, even though sampleswere taken out to 504 hours. The absorption of the mAb following SCdosing appears to reach a steady-state with elimination throughout theduration of the study.

EXAMPLE 36 IL-20 and IL-22 Antagonists in CD4⁺CD45RB^(hi) (CD25⁻)Colitis and Psoriasis Model

A. Summary

Transfer of CD4+ CD45RB^(hi) or CD4+CD25− T cells intosyngeneic SCIDmice results in colitis in the mice. Co-transfer of regulatory T cells(CD4+CD25+ or CD4+CD45RB^(lo)) inhibits this colitis. After transfer ofCD4+CD25− T cells into mice, if mice are additionally injected withstaphylococcal enterotoxin B (SEB), mice not only develop colitis, butalso psoriasis. Antibodies against IL-22RA, IL-20, IL-22, IL20R and/orIL-22R, or soluble IL-22RA receptors are administered from days 0-21after cell transfer and symptoms for colitis and psoriasis aremonitored. Inhibition of psoriatic score or colitis (histology)indicates that IL-21 can inhibit these autoimmune diseases.

B. Study Design

Spleens and inguinal lymph nodes are isolated from B 10.D2 mice. Singlecell suspensions are formed and counted. Using the Miltenyi Bead system,CD25+ cells are sorted out by positive selection. Cells are stained withCD25-PE (BD Pharmingen) at 1:100 dilution and incubated for 15 minutes.Excess antibody is washed out and the cells are incubated with 10 ulanti-PE beads/10⁶ cells for 20 minutes. The cells are washed with PBSand passed over an LS column (Miltenyi Biotech). Cells that pass throughthe column (CD25−) are retained for further analysis. A CD4 enrichmentcocktail (Stem Cell technologies) is added (1:100) to these CD25− cellsand incubated for 15 minutes. Cells are washed with PBS. A 1:10 dilutionof anti-biotin tetramer is added to the cells for 15 minutes followed bya magnetic colloid (60 ul/10⁶ cells) for 15 minutes (all from Stem CellTechnologies). Cells are passed through a negative selection column(0.5″, Stem cell Technologies). Cells that pass through are theCD4+CD25− cells. Purity is analyzed using flow cytometry. 0.4×10⁶ cellsare injected i.v into naïve CB-17 SCID mice in a total volume of 200 μl.Mice are injected i.p with 10 μg SEB the following day (d1). Symptomsfor psoriasis and colitis are followed from 2-5 weeks. Mice are scoredfor psoriasis disease under the following criteria. 0—no lesions, 1—mildlesions on the neck, 2—severe lesions on the neck and back (trunk)3—very severe lesions on the neck, back and the belly of mice. Earthickening is also measured as a measure of disease severity. Groups ofmice are injected i.p. with PBS, 100 μg control antibody or 10-100 μgantibodies against IL-22RA, IL-20, IL-22, IL-20R or IL-22R, or solubleIL-22RA from days 1-30 under different dosing regimen (3×/week or2×/week).

C. Results and Conclusion

Inhibition of psoriatic and colitis symptoms in antibody treated miceindicates that inhibition of IL-20 and/or IL-22 function can inhibitautoimmune symptoms in this model for psoriasis and colitis.

EXAMPLE 37 IL-20, and IL-22 Antagonists in SCID-hu Transplant PsoriasisModel

Human psoriasis skin grafted on SCID mouse can maintain its clinical,light microscopic, and immunohistochemical psoriatic features forseveral weeks. This model provides a system for evaluating therapiesintended to restore lesional tissue to a normal phenotype. Once thehuman skin is successfully grafted, antibodies against IL-22RA, IL-20,IL-22, IL-20R and/or IL-22R, or soluble IL-20 or IL-22 receptors can beadministered for several weeks, and the epidermal thickness can beanalyzed to evaluate the effect of these antagonists on psoriasis.

A. Study Design

Full-thickness 6-mm punch biopsies consisting of the entire epidermisand several mm of dermis are obtained healthy adult volunteers andpsoriatic lesional skins. Four to six biopsies are obtained from eachdonor. One punch biopsy from each donor is transplanted onto the dorsalsurface of recipient SCID mouse (CB-17, Taconic). The animals aremaintained in a pathogen-free environment. The treatment is initiatedafter a successful grafting (2-3 weeks post-transplantation) asfollowing: one biopsy for negative control (PBS or isotype mAb), onebiopsy for positive control (Cyclosporin A), and 2-3 biopsies fortreatment with anti-human IL-22RA, anti-human IL-20, anti-human IL-22mAb or soluble receptors for IL-20 or IL-22 (intraperitoneal injection,three times a week for 2-4 weeks on a M-W-F schedule).

B. Quantitative Analysis:

Clinical observations and assessments will be made regularly throughoutthe experiments, and will be recorded. The severity of the psoriaticlesions is assessed for scaliness, induration, and erythema in a blindedfashion. The parameters can be scored using the three-point scale:0=complete lack of cutaneous involvement; 1=slight involvement;2=moderate involvement; 3=severe involvement. At the end of the dosingperiod each animal is euthanized and tissues are collected for histologyand IHC. (1) Part of the tissue is fixed in 10% formalin and stainedwith hematoxylin and eosin. Epidermal area is measured as a function ofchanges in epidermal thickness per unit length using NIH Image software.Multiple areas from each transplant are quantified to provide a high nvalue and mean epidermal area. (2) number of inflammatory mononuclearcells per high-power field (0.103×0.135 mm) in the upper dermis; (3) thegrade of parakeratosis is rated on an arbitrary scale from 0 to 3, where0 is no parakeratosis, 1 is parakeratosis in less than one third of thesection, 2 was parakeratosis in more than one third but less than twothirds of the section, a d 3 is parakeratosis in more than two thirds ofthe section. (4) The remaining of the tissue will be stained for Ki67(marker of proliferating keratinocytes), to evaluate the number of Ki67cycling keratinocytes-per-millimeter length of the section. The reducedseverity of psoriasis as measured by epidermal thickness, indicates theneutralization of IL-20 and IL-22 function can be effective in thispsoriasis model. To quantify the reduced severity of psoriasis, wemeasure epidermal thickness, the number of inflammatory cells in theupper dermis, the numbers of Ki67 cycling keratinocytes, and the gradesof parakeratosis. The significantly reduced all four parameters for thetreated groups compared to the control mice, indicate the potentialtherapeutic use of IL-20, IL-22 antagonists.

EXAMPLE 38 Screening for IL-20 Antagonist Activity UsingBaF3/IL-22RA/IL-20RB Cells Using an Alamar Blue Proliferation Assay

The factor-dependent pre-B cell line BaF3 was co-transfected withIL-22RA and IL-20RB (see, method in Example 3) and treated with IL-20 atvarious concentrations. Proliferation was assessed using an alamar blueassay as described in Example 3. IL-20 stimulated proliferation in adose-dependent manner at concentrations expected for a cytokine,demonstrating that IL-20 binds and activates the heterodimericIL-22RA/IL-20RB receptor at concentrations expected for a cytokine. Thenegative controls containing untransfected BaF3 did not proliferate.

In order to determine if anti-IL-22RA antibodies are capable ofantagonizing IL-20 activity, the assay described above is performedusing anti-IL-22RA antibodies as an antagonist to IL-20 activity. WhenIL-20 is combined with such antagonist, the response to IL-20 is broughtdown to background levels. That the presence of an antagonist thatablates or reduces the proliferative effects of IL-20 demonstrates thatit is an antagonist of the IL-20 ligand. This assay can be used to testother antagonists of IL-20 activity described herein, such as antagonistpolypeptides comprising a soluble IL-22RA receptor.

EXAMPLE 39 Neutralization of IL-20 and IL-22 Activity by Anti-huL22RAMonoclonal Antibody

Using the cell-based neutralization assay described in Example 28, apurified mouse anti-huIL-22RA monoclonal antibody (Example 30(D)) wasadded as a serial dilution, for example, at 10 ug/ml, 5 ug/ml, 2.5ug/ml, 1.25 ug/ml, 625 ng/ml, 313 ng/ml, 156 ng/ml and 78 ng/ml. Theassay plates were incubated at 37° C., 5% CO₂ for 4 days at which timeAlamar Blue (Accumed, Chicago, Ill.) was added at 20 μl/well. Plateswere again incubated at 37° C., 5% CO₂ for 16 hours. Results showed thatthe purified anti-huIL-22RA monoclonal antibody could neutralizesignalling of both huIL-22 and huIL-20 through huIL-22RA. At the 10ug/ml concentration, the antibody completely neutralized proliferationinduced by huIL-22 or huIL-20, with the inhibition of proliferationdecreasing in a dose dependent fashion at the lower concentrations. Anisotype-matched negative control mouse mAb, tested at the concentrationsdescribed above, provided no inhibition of proliferation of eithercytokine. These results further demonstrate that monoclonal antibodiesto IL-22RA could indeed antagonize the activity of the pro-inflammatoryligands, IL-20 and IL-22 at low concentrations.

These results provided additional evidence that effectively blockingIL-22RA activity, for example via a neutralizing monoclonal antibody toIL-22RA of the present invention, could be advantageous in blocking,inhibiting, reducing, antagonizing or neutralizing the effects of IL-20and IL-22 (alone or together) in vivo and maybe reduce IL-20 and/orIL-22-induced inflammation, such as that seen in IL-20-induced skineffects, as well as IL-22-induced skin effects, for example inpsoriasis, IBD, colitis, or other inflammatory diseases induced byIL-20, and or IL-22 including IBD, arthritis, asthma, psoriaticarthritis, colitis, inflammatory skin conditions, and atopic dermatitis.

EXAMPLE 40 Treatment of Pregnant IL-20 and IL-22 Transgenic Mice withNeutralizing Anti-IL-22RA Monoclonal Antibody

To test the rat anti-mouse IL-22RA monoclonal antibody (mAb) forneutralizing activity in vivo, pregnant IL-20 transgenic (Tg) and IL-22Tg mice are injected intraperitoneally with an anti-mouse IL-22RA mAb.The newborn pups are then assessed for the presence or absence of the“shiny” skin phenotype that normally characterizes these strains ofmice.

Specifically, male IL-20 Tg (which are generated using the keratin-14)or IL-22 Tg (using the insulin promoter) mice are bred to C57BL/6Nfemales in estrus and the bred females are identified by the presence ofa vaginal plug the following day. Each pregnant female is set aside in aseparate cage and monitored daily. Treatment groups include at least 4pregnant females each, to allow for a statistically significant analysisof both Tg and nonTg pups. Based on prior experience with these Tg mice,a litter usually ranges between approximately 6 to 8 pups per litter, ofwhich between 2 to 3 are Tg+.

Seven to nine days after the mice are bred (embryonic age 7-9; e7-9),the females are injected intraperitoneally with 250-500 ug of the ratanti-mouse IL-22RA mAb (rat IgG2a isotype) in a volume of 200-250 ul ofPBS. Short needles are used at a shallow injection angle to avoiddirectly injecting the uterus. The pregnant females are injected in thismanner 3 days a week (Monday, Wednesday, and Friday) for 2 weeks (untilbirth) in order to successfully access the developing embryos. Controlgroups (of not less than 4 pregnant female mice each) include thefollowing: isotype control rat IgG2a mAb, anti-human/mouse IL-22 mAb(rat IgG1 isotype), and an isotype control rat IgG1 mAb. As a controlfor neutralization of murine IL-20, pregnant females are injected witheither a soluble IL-20R-Fc4 fusion protein that can bind and neutralizeboth human and murine IL-20 or an Fc4 control protein.

From days 1 to 2 after birth, the pups are closely monitored for theappearance of the shiny skin phenotype. On day 2, the pups areeuthanized and a portion of the tail is collected for DNA isolation todetermine the genotype (Tg or nonTg) of each pup. Skin samples arecollected for histological analysis in order to assess whether the pupsexhibit the thickened epidermal cell layers that usually characterizethese Tg mice. Trunk blood is also collected from the pups (and aneyebleed from the dams one day after birth) to quantitate, via ELISA,the levels of anti-IL-22RA mAb in the serum of each mouse. Because thesemAbs are potent inhibitors of IL-20 and/or IL-22 in vivo, the Tg pupshave normal skin (i.e. no epidermal thickening or “shiny” appearance).

EXAMPLE 41 IL-20 and IL-22 Antagonists in Organ Culture Psoriasis Model

Human psoriatic plaque skin can be maintained in organ culture, and theabnormal histological features of lesional skin are maintained in theabsence of exogenous growth factors. Antibodies against IL-22RA, IL-20,IL-22, IL20R and/or IL-22R, or soluble IL-20 or IL-22 receptors can beadministered, and the histological features of psoriatic lesional skincan be ameliorated.

A. Study Design

Full-thickness 2-mm punch biopsies consisting of the entire epidermisand several mm of dermis are obtained from either healthy adultvolunteers or from psoriatic lesional skin. Immediately upon biopsy, thetissue is immersed in culture medium consisting of Keratinocyte BasalMedium (KBM) (Clonetics Inc, Walkersville, Md.). The culture medium issupplemented with CaCl2 to bring the final Ca2+ concentration to 1.4 mM(Varani et al, 1993, 1994). The biopsies are then incubated in wells ofa 96-well dish containing 200 ul of Ca2+ supplemented KBM with orwithout additional treatments of antibodies against human IL-20, IL-22,IL-22RA, or soluble receptors of IL-20 or IL-22. Cultures are incubatedat 37° C. in an atmosphere of 95% air and 5% CO₂ for 8 days.

B. Quantitative Analysis:

At the end of incubation period, tissue is fixed in 10% bufferedformalin and examined histologically after staining with hematoxylin andeosin. The appearance of psoriatic tissue exposed to the antibodies orsoluble receptors could be more closely resembled that of normaltissues, including the following observation: the initiallydisorganized, irregular-shaped basal epithelial cells developed a morecolumnar appearance with restored polarity; epidermal rete ridgesregressed, with fewer areas of epithelial cell expansion into the dermalspace; and there was less overall degeneration of the upper epidermallayers. The organ culture model provides a rapid and sensitive means fordetermining if a particular compound has potential as ananti-hyperproliferative agent. The abnormal histological feature may beameliorated in the presence of an IL-20, IL-22 antagonist, suggestingthe effectiveness of such agent in the treatment of psoriasis.

EXAMPLE 42 Mapping of mIL22RA (zCytoR11m) Regions Binding toNeutralizing mAbs R2.1.5F4.1 and R2.1.15E2.1

A. Epitopes on Murine IL-22RA Wherein Neutralizing Monoclonal AntibodiesBind.

The experiments described below were aimed at identifying a region orregions in the amino acid sequence of murine IL-22RA soluble receptorprotein (SEQ ID NO:62) that were important for receptor activity, or forantagonist or neutralizing antibody binding. The murine IL-22RA-Fcprotein, which was previously cleaved with thrombin to remove the Fc,was then cleaved C-terminally to the methionine residues in the sequenceby incubation with cyanogen bromide (CNBr). The CNBr-generated peptideswere fractionated, and fractions were tested for binding activity asdetected by ELISA and reactivity by Western analysis using monoclonalantibodies with neutralizing properties, clones R2.1.5F4.1 andR2.1.15E2.1.

Upon cleavage with CNBr, the following peptides were potentiallygenerated from non-reduced full-length mIL-22RA (Table 33). Undernon-reducing conditions, cysteines are disulfide-bonded, which mayresult in an internal linkage in peptide 1 and a link between peptides 3and 5. The residues in bold font are potentially involved in ligandbinding that correspond with human IL-22RA residues potentially involvedin ligand binding in SEQ ID NO:2 or SEQ ID NO:3, as described in Example42B. Specifically, SEQ ID NO:48 corresponds to amino acid residues 16(His) to 83 (Met) of SEQ ID NO:42; SEQ ID NO:49 corresponds to aminoacid residues 84 (Glu) to 109 (Met) of SEQ ID NO:42, SEQ ID NO:50corresponds to amino acid residues 110 (Thr) to 137 (Met) of SEQ IDNO:42, SEQ ID NO:51 corresponds to amino acid residues 138 (Leu) to 177(Met) of SEQ ID NO:42, and SEQ ID NO:52 which corresponds to amino acidresidues 163 (His) to 208 (Pro) of SEQ ID NO:42 or 163 (His) to 212(Arg) of SEQ ID NO:62.

TABLE 33 Peptide Number From To Sequence CNBr Peptide 1   1  68HTTVDTSGLLQHVKFQSSNFENILTWDG GPASTSDTVYSVEYKKYGERKWLAKAGC QRITQKFCNLTM(SEQ ID NO: 48) non-reduced: cysteines in peptide 1 are linked CNBrPeptide 2  69  94 ETRNHTEFYYAKVTAVSAGGPPVTKM (SEQ ID NO: 49) CNBrPeptide 3  95 122 TDRFSSLQHTTIKPPDVTCIPKVRSIQM (SEQ ID NO: 50)non-reduced: peptides 3-5 are linked CNBr Peptide 4 123 162LVHPTLTPVLSEDGHQLTLEEIFHDLFY RLELHVNHTYQM (SEQ ID NO: 51) CNBr Peptide 5163 212 HLEGKQREYEFLGLTPDTEFLGSITILT PILSKESAPYVCRVKTLPLVPR (SEQ ID NO:52)

1. CNBr Cleavage and Isolation of Peptide Fractions

50 μg of mIL22RA was lyophilized and reconstituted in 180 μL of formicacid (70%). 1 μL of 5M CNBr dissolved in acetonitrile was added. Thesample was mixed and left to react for 18 hours at room temperature inthe dark. 150 μL of the reaction mixture were fractionated byreversed-phase HPLC fitted with an analytical Zorbax SB300-C8 column.Peaks were separated using a gradient starting at 25% acetonitrile(0.085% TFA) and 75% water (0.1% TFA) and finishing at 95% acetonitrile(0.085% TFA) and 5% water (0.1% TFA). UV analysis showed three main andtwo minor peaks, which were collected. Each fraction was divided inhalf, one portion was submitted to ELISA, the other portion waslyophilized and reconstituted in 150 μL of phosphate-buffered salinesolution (PBS). UV analysis of the PBS fractions confirmed the recoveryof all peaks collected from the analytical column. The PBS fractionswere submitted for Western analysis.

2. ELISA

HPLC fractions containing peptide sequences from IL-22RA cleaved withCNBr were diluted to an estimated equal concentration using HPLC buffer(90% acetonitrile, 10% H₂O, 0.09% trifluoroacetic acid). Samples wereloaded to ninety-six-well microtiter plates in 4 wells each at 100μL/well and allowed to dry down overnight at room temperature in a fumehood. The plates were washed with ELISA C buffer (PBS, 0.05% Tween-20),and then blocked with ELISA B buffer (PBS, 0.1% BSA, 0.05% Tween-20) for2 hours at 37° C. Two monoclonal antibodies (mAb) to IL22RA (CloneR2.1.5F4.1, and Clone R2.1.15E2.1) were diluted to 2 μg/mL in ELISA B.Each mAb was added to each peptide sequence sample at 100 μL/well andplates were incubated for 60 minutes at 37° C. The plates were washed toremove unbound antibody, and a secondary antibody (goat anti-rat IgGconjugated to horseradish peroxidase (Jackson)) was diluted to 1 μg/mLin ELISA B buffer and added to all wells at 100 μL/well. Plates wereincubated for 1 hour at 37° C. The wells were washed with ELISA Cbuffer, and then incubated with TMB 1 Component HRP Microwell Substrate(BioFx) for 5 minutes. The reaction was stopped by the addition of 450nm Stop Reagent for TMB Microwell (BioFx) and the plates read atabsorbance 450 nm in a Dynatech ELISA plate reader (Molecular Devices).

Results indicate mAb R2.1.5F4.1 reacted with HPLC fraction #4 of themIL22RA CNBr reaction, which also produced a band in the Westernblotting experiments.

3. Western

HPLC fractions containing peptide sequences from IL22RA cleaved withCNBr were lyophilized over night at room temp, and reconstituted in PBS.Samples were then mixed with non-reducing sample buffer (Invitrogen) andboiled for 10 min. Samples were loaded and electrophoresed by SDS-PAGEon 4-12% Bis-Tris gels (Invitrogen) using 1×MES-SDS Running Buffer(Invitrogen) and transferred to nitrocellulose (0.2 μm; Bio-Rad) in 20%Methanol transfer buffer, all at room temperature. Filters were allowedto dry over night at room temperature. The filters were blocked with 10%non-fat dry milk in buffer A (50 mM Tris, pH 7.4, 5 mM EDTA, 0.05%Igepal CA-630, 150 mM NaCl, 0.25% gelatin) for 30 minutes at roomtemperature. A monoclonal antibody (mAb) to IL22RA (Clone R2.1.5F4.1)was diluted to 2 μg/mL in buffer A containing 2.5% non-fat dry milk.Blots were incubated in this primary antibody for 1 hour at roomtemperature. Following incubation, blots were washed three times inbuffer A and incubated 1 hour at room temperature with a 1:5000 dilutionof secondary antibody (Goat anti-Rat IgG-horseradish peroxidase;Jackson, Inc) in buffer A with 2.5% non-fat dry milk. The blots werethen washed, developed with a chemiluminescent substrate (Lumi-LightWestern Blotting Substrate; Roche), and exposed using a luminescentimager (Mannheim Boehringer Lumi-Imager).

Using a 30 minute exposure, the non-reducing gel showed very strongbands for fractions #4 and #5, along with a faint band for fraction #3.Fraction #4 also tested positive in the ELISA.

N-Terminal Sequencing of Active Fraction #4

Of the five CNBr peptide fractions collected from the analyticalreversed-phase column, fraction #4 showed activity in the ELISA and wasalso positive by Western blotting. To identify the peptides present inthe active fraction #4, the sample was submitted to Edman degradationusing well-known methods. Three N-termini were identified from theactive fraction that were consistent with peptides 2 (SEQ ID NO:49), 3(SEQ ID NO:50), and 5 (SEQ ID NO:52). These results indicated that theantibodies bound to peptides 2 (SEQ ID NO:49), 3 (SEQ ID NO:50), and 5(SEQ ID NO:52).

TABLE 34 Peptide Edman Degradation N-Terminal Sequence IdentificationFirst Sequence Obtained from Fraction #4 HLEGK QREYE FLGLT CNBr Peptide5 PDTEF (SEQ ID NO: 52) CNBr-generated mIL22RA Sequence HLEGK QREYEFLGLT PDTEF LGSIT ILTPI LSKES APYVC RVKTL PLVPR (SEQ ID NO: 53) SecondSequence Obtained from Fraction ETRNH TEFYY AKVTA CNBr Peptide 2 #4VSAGG (SEQ ID NO: 49) CNBr-generated mIL22RA Sequence ETRNH TEFYY AKVTAVSAGG PPVTK M (SEQ ID NO: 54) Third Sequence Obtained from Fraction #4TDRFS XLQHT XIXPX CNBr Peptide 3 DXXXI (SEQ ID NO: 50) CNBr-generatedmIL22RA Sequence TDRFS SLQHT TIKPP DVT+E,UNS C+EE I PKVRS IQM (SEQ IDNO: 55)Discussion

Five fractions were isolated from a mixture of CNBr-cleaved mIL22RApeptides. Of these, only fraction #4 was active in an ELISA and positiveby Western. Edman degradation identified three N-termini consistent withCNBr peptides 2 (SEQ ID NO:49), 3 (SEQ ID NO:50), and 5 (SEQ ID NO:52)in fraction #4. Within these regions, six residues are potentiallyinvolved in ligand binding. These residues are Y93, R112, K210, and E211of SEQ ID NO:42, which also correspond to residues Y78, R97, K195, andE196 of SEQ ID NO:62. Residues Y60 and F164 of SEQ ID NO:42 are alsoinvolved in ligand binding.

B. Epitopes on Human IL-22RA Wherein Neutralizing Monoclonal AntibodiesBind.

The experiments described below are aimed at identifying a region orregions in the extracellular domain for amino acid sequence of humanIL-22RA protein (SEQ ID NO:2) that are important for receptor activity,or for antagonist or neutralizing antibody binding. A human solublereceptor IL-22RA protein (e.g., comprising SEQ ID NO:3, such as,IL-22RA-Fc cleaved with thrombin to remove the Fc) is then cleavedC-terminally to the methionine residues in the sequence by incubationwith cyanogen bromide (CNBr), or other agent known in the art thatcleaves the human protein into defined fragments. The CNBr-generatedpeptides are fractionated, and the resulting fractions are tested forbinding activity as detected by ELISA and reactivity by Western analysisusing monoclonal antibodies with neutralizing properties.

Four cysteines are predicted to be disulfide-bonded with a linkagepattern of Cys71-Cys79 and Cys204-Cys217 of SEQ ID NO:2. Upon cleavagewith CNBr, the following peptides are potentially generated fromnon-reduced full-length human IL-22RA: peptide 6 (SEQ ID NO:56), peptide7 (SEQ ID NO:57); peptide 8 (SEQ ID NO:58); peptide 9 (SEQ ID NO:59);peptide 10 (SEQ ID NO:60); and peptide 11 (SEQ ID NO:61) (Table 35).Cysteines are disulfide-bonded, which results in a possible link betweenpeptides 7 (SEQ ID NO:57) and 10 (SEQ ID NO:60. Specifically, SEQ IDNO:56 corresponds to amino acid residues 1 (Pro) to 92 (Met) of SEQ IDNO:3; SEQ ID NO:57 corresponds to amino acid residues 93 (Thr) to 120(Met) of SEQ ID NO:3, SEQ ID NO:58 corresponds to amino acid residues121 (Ile) to 160 (Met) of SEQ ID NO:3, SEQ ID NO:59 corresponds to aminoacid residues 161 (His) to 185 (Met) of SEQ ID NO:3, SEQ ID NO:60corresponds to amino acid residues 186 (Ile) to 199 (Met) of SEQ ID NO:3and SEQ ID NO:61 corresponds to amino acid residues 200 (Cys) to 211(Thr) of SEQ ID NO:3.

TABLE 35 Peptide Number From To Sequence CNBr Peptide 6 1 92 Pro Glu AspPro Ser Asp Leu Leu Gln His Val Lys Phe Gln Ser Ser Asn Phe Glu Asn IleLeu Thr Trp Asp Ser Gly Pro Glu Gly Thr Pro Asp Thr Val Tyr Ser Ile GluTyr Lys Thr Tyr Gly Glu Arg Asp Trp Val Ala Lys Lys Gly Cys Gln Arg IleThr Arg Lys Ser Cys Asn Leu Thr Val Glu Thr Gly Asn Leu Thr Glu Leu TyrTyr Ala Arg Val Thr Ala Val Ser Ala Gly Gly Arg Ser Ala Thr Lys Met (SEQID NO: 56) CNBr Peptide 7 93 120 Thr Asp Arg Phe Ser Ser Leu Gln His ThrThr Leu Lys Pro Pro Asp Val Thr Cys Ile Ser Lys Val Arg Ser Ile Gln Met(SEQ ID NO: 57) CNBr Peptide 8 121 160 Ile Val His Pro Thr Pro Thr ProIle Arg Ala Gly Asp Gly His Arg Leu Thr Leu Glu Asp Ile Phe His Asp LeuPhe Tyr His Leu Glu Leu Gln Val Asn Arg Thr Tyr Gln Met (SEQ ID NO: 58)CNBr Peptide 9 161 185 His Leu Gly Gly Lys Gln Arg Glu Tyr Glu Phe PheGly Leu Thr Pro Asp Thr Glu Phe Leu Gly Thr Ile Met (SEQ ID NO: 59) CNBrPeptide 10 186 199 Ile Cys Val Pro Thr Trp Ala Lys Glu Ser Ala Pro TyrMet (SEQ ID NO: 60) CNBr Peptide 11 200 211 Cys Arg Val Lys Thr Leu ProAsp Arg Thr Trp Thr (SEQ ID NO: 61)

4. CNBr Cleavage and Isolation of Peptide Fractions, Western and ELISA,and N-terminal Sequencing

About 50 μg of human IL22RA is lyophilized and is reconstituted,fractionated, collected and analysed using Western analysis, and ELISAas described in EXAMPLE 42A, to identify fractions containinganti-IL-22RA monoclonal antibodies, and those that bind IL-22RA as shownby ELISA and Western analysis. The CNBr peptide fractions that arecollected from the analytical reversed-phase column, are then tested foractivity in the ELISA and are confirmed as positive by Western blotting.For positive fractions, peptides are identified via Edman degradationusing well-known methods.

Discussion

The mouse CNBr peptide #5 (SEQ ID NO:52) corresponds to human CNBrpeptides #9, and #10 (SEQ ID NO:59 and SEQ ID NO:60); mouse CNBr peptide#2 (SEQ ID NO:49) corresponds to human CNBr #6 (SEQ ID NO:56); and mouseCNBr peptide #3 (SEQ ID NO:50) corresponds to human CNBr #7 (SEQ IDNO:57). Of the fractions that are isolated from a mixture theCNBr-cleaved human IL-22RA peptides, six residues within the possibleregions are potentially involved in ligand binding: Residues of SEQ IDNO:2 (and corresponding residues of SEQ ID NO:3) that are important toligand-receptor binding comprise Tyr-60, and Phe-164, Tyr-93, Arg-112,Lys-210, and Glu-211 of SEQ ID NO:2 and (and corresponding residues ofSEQ ID NO:3). Moreover, primary residues of SEQ ID NO:2 (andcorresponding residues of SEQ ID NO:3) that are important to directligand-receptor binding comprise Tyr-60, and Phe-164 of SEQ ID NO:2 (andcorresponding residues of SEQ ID NO:3), and secondary residues compriseresidues Tyr-93, Arg-112, Lys-210, and Glu-211 of SEQ ID NO:2 and (andcorresponding residues of SEQ ID NO:3).

From the foregoing, it will be appreciated that, although specificembodiments of the invention have been described herein for purposes ofillustration, various modifications may be made without deviating fromthe spirit and scope of the invention. Accordingly, the invention is notlimited except as by the appended claims.

1. A humanized antibody that specifically binds to a polypeptide asshown in SEQ ID NO:2 or SEQ ID NO:3, wherein said humanized antibody isderived from an antibody expressed by a hybridoma selected from thegroup consisting of: (a) the hybridoma clone 280.46.3.4 (ATCC PatentDeposit Designation PTA-6284); (b) the hybridoma clone 281.73.49.1.1(ATCC Patent Deposit Designation PTA-6285); (c) the hybridoma clone283.4.1.2 (ATCC Patent Deposit Designation PTA-6287); (d) the hybridomaclone 283.52.5.4 (ATCC Patent Deposit Designation PTA-6311); and (e) thehybridoma clone 283.108.2.3 (ATCC Patent Deposit Designation PTA-6286).2. The humanized antibody of claim 1, wherein said humanized antibody isderived from the antibody expressed by the hybridoma clone 280.46.3.4.3. The humanized antibody of claim 1, wherein said humanized antibody isderived from the antibody expressed by the hybridoma clone281.73.49.1.1.
 4. The humanized antibody of claim 1, wherein saidhumanized antibody is derived from the antibody expressed by thehybridoma clone 283.4.1.2.
 5. The humanized antibody of claim 1, whereinsaid humanized antibody is derived from the antibody expressed by thehybridoma clone 283.52.5.4.
 6. The humanized antibody of claim 1,wherein said humanized antibody is derived from the antibody expressedby the hybridoma clone 283.108.2.3.
 7. A pharmaceutical compositioncomprising the humanized antibody according to any one of claims 1 to 6.